(SURFSIDE, Fla.) — At least 16 people are dead and 147 others remain unaccounted for after a 12-story residential building partially collapsed in South Florida’s Miami-Dade County last week, officials said.

A massive search and rescue operation entered its seventh day on Wednesday as crews continued to carefully comb through pancaked piles of debris in hopes of finding survivors. The partial collapse occurred around 1:15 a.m. local time Thursday at the Champlain Towers South condominium in the small, beachside town of Surfside, about 6 miles north of Miami Beach. Approximately 55 of the oceanfront complex’s 136 units were destroyed, according to Miami-Dade Fire Rescue Assistant Chief Raide Jadallah.

So far, 139 people who were living or staying in the condominium at the time of the disaster have been accounted for and are safe, according to Miami-Dade County Mayor Daniella Levine Cava, who stressed that the numbers are “very fluid” and “continue to change.” Officials previously were including the number of deceased among those accounted for but are now separating the figures.

“Our teams have worked through the night, as they have every night, to make headway through the rubble,” Levine Cava said during a press conference in Surfside on Wednesday. “The world is watching.”

‘We’re not going to leave anybody behind’

The remaining structure was cleared by rescue crews last week, and all resources have since been shifted to focusing on the debris, according to Jadallah. Hundreds of first responders and volunteers have been working around the clock to locate any survivors or human remains in the wreckage. However, poor weather conditions — among other challenges — have periodically forced them to pause their efforts.

“It’s been tough,” Miami-Dade Fire Rescue Chief Alan Cominsky said at the press conference Wednesday morning, before noting that crews are “hoping for a positive outcome.”

“The spirits are high,” he added. “We’re still moving forward.”

Surfside Mayor Charles Burkett told reporters that there have been questions from families about when the efforts will transition from search and rescue to recovery. But he said there’s a strong consensus among officials and rescuers: “We’re not going to leave anybody behind.”

“This is going to go on until we get everybody out of there,” Burkett said at the press conference Wednesday morning.

Crews have cut a vast trench through the pile to aid in their search, according to Levine Cava. As of Tuesday afternoon, they had moved more than 3 million pounds of concrete — over 850 cubic feet — according to Cominsky.

Meanwhile, dump trucks have begun moving debris to an alternate site, according to Kevin Guthrie, director of the Florida Division of Emergency Management, who told reporters that rescuers have “all the resources” they need.

Crews have still not physically reached the bottom of the pile but cameras placed inside showed voids and air pockets where people could be trapped, according to Jadallah.

More than 80 rescuers — each working 12-hour shifts — are on the pile at a time, listening for sounds and trying to tunnel through the wreckage, according to Andy Alvarez, the Miami-Dade Fire Rescue’s deputy incident commander overseeing search and rescue efforts. Speaking to ABC News on Monday, Alvarez described the process as both “frantic” and painstaking.

The conditions on the pile are “bad” and “not ideal” for rescuers, Alvarez said, due to heat, humidity and rain, but efforts are continuing around the clock. Crews are using various equipment and technology, including underground sonar systems that can detect victims and crane trucks that can remove huge slabs of concrete from the pile, according to Alvarez.

The site also has proven to be dangerous for rescuers. One area had to be roped off Tuesday due to falling debris, according to Burkett, and crews are no longer entering the remaining structure because it’s considered unstable, Levine Cava told reporters.

“We’re exhausting every avenue here but it’s a very, very dangerous situation and I can’t understate that,” Cominsky said at the press conference Wednesday morning.

It’s the largest-ever deployment of task force resources in state history for a non-hurricane event. But as the Atlantic hurricane season ramps up, officials are monitoring storms in the region in case some resources deployed to Surfside are needed elsewhere, according to Florida Gov. Ron DeSantis.

“‘Tis the season, and you’ve got to be ready,” DeSantis said at the press conference on Wednesday.

Some of the first responders are members of the Miami-Dade Fire Rescue’s urban search and rescue team, Florida Task Force-1, which is part of the Federal Emergency Management Agency’s National Urban Search and Rescue Response System and has been deployed to disasters across the country and around the world. Search and rescue teams from Israel and Mexico have also joined the efforts in Surfside.

Although officials have continued to express hope that more people will be found alive, no survivors have been discovered in the rubble of the building since the morning it partially collapsed. Bodies, however, have been uncovered throughout the site, which crews have categorized into grids, according to Cominsky. The fire chief told reporters that rescuers with specially trained dogs are still “constantly” “searching for life” amid the debris.

Officials have asked families of the missing to provide DNA samples and unique characteristics of their loved ones, such as tattoos and scars, to help identify those found in the wreckage. Detectives are also in the process of conducting an audit of the list of those accounted and unaccounted for, according to Levine Cava.

“The process of verifying every name on this list is very slow and methodical,” the Miami-Dade County mayor said at the press conference Wednesday morning. “Sometimes we receive incomplete reports, we don’t have the full information, it’s difficult to reach the people who provided the reports.”

President Joe Biden and first lady Jill Biden will travel to Surfside on Thursday, according to a statement from the White House. Last week, the president approved an emergency declaration in Florida and ordered federal assistance to supplement state and local response efforts in the wake of the partial building collapse.

Investigation ‘will take a long time’

The cause of the partial collapse to a building that has withstood decades of hurricanes remains unknown. The Miami-Dade Police Department is leading an investigation into the incident.

“We are doing everything humanely possible — and then some — to get through this tragedy and we are doing it together,” Levine Cava said at the press conference Wednesday morning.

The Miami-Dade County mayor told ABC News last Friday that there was no evidence of foul play so far but that “nothing’s ruled out.”

Miami-Dade State Attorney Katherine Fernandez Rundle said she plans “to request that our Grand Jury look at what steps we can take to safeguard our residents without jeopardizing any scientific, public safety, or potential criminal investigations.”

“I know from personally speaking with engineers from the National Institute of Standards and Technology that their investigation to determine exactly how and why the building collapsed will take a long time,” Rundle said in a statement Tuesday. “However, this is a matter of extreme public importance, and as the state attorney elected to keep this community safe, I will not wait.”

Built in the 1980s, the Champlain Towers South was up for its 40-year recertification and had been undergoing roof work, according to Surfside officials.

The partial collapse happened as the Champlain Towers South Condo Association was preparing to start a new construction project to make updates, according to Kenneth Direktor, a lawyer for the association. Direktor told ABC News last Thursday that the building had been through extensive inspections and the construction plans had already been submitted to the town but the only work that had begun was on the roof.

Direktor noted that he hadn’t been warned of any structural issues with the building or about the land it was built on. He said there was water damage to the complex, but that is common for oceanfront properties and wouldn’t have caused the partial collapse.

A 2020 study conducted by Shimon Wdowinski, a professor at Florida International University’s Institute of Environment in Miami, found signs of land subsidence from 1993 to 1999 in the area where the Champlain Towers South condominium is located. But subsidence, or the gradual sinking of land, likely would not on its own cause a building to collapse, according to Wdowinski, who analyzed space-based radar data.

Miami-Dade County officials are aware of the study and are “looking into” it, Levine Cava told ABC News last Friday.

Records show structural damage, concerns over nearby construction

A structural field survey report from October 2018, which was among hundreds of pages of public documents released by the town late Sunday, said the waterproofing below the condominium’s pool deck and entrance drive was failing and causing “major structural damage to the concrete structural slab below these areas.” The New York Times first reported the news.

In a November 2018 email, also released by the town, a Surfside building official, Ross Prieto, told the then-town manager that he had met with the Champlain Towers South residents and “it went very well.”

“The response was very positive from everyone in the room,” Prieto wrote in the email. “All main concerns over their forty year recertification process were addressed. This particular building is not due to begin their forty year until 2021 but they have decided to start the process early which I wholeheartedly endorse and wish that this trend would catch on with other properties.”

A former resident, Susanna Alvarez, told ABC News on Sunday that Prieto said during the 2018 meeting that the condominium was “not in bad shape” — a sentiment that appears to conflict with the structural field survey report penned five weeks earlier.

ABC News obtained a copy of the minutes from the November 2018 meeting of the Champlain Towers South Condo Association, which stated that Prieto had reviewed the structural field survey report and “it appears the building is in very good shape.” NPR was the first to report the news.

Prieto has not responded to ABC News’ repeated requests for comment. He is no longer employed by the town of Surfside. He has been placed on a “leave of absence” from his current post as a building inspector in nearby Doral, according to a statement from the city on Tuesday.

When asked on Monday whether Prieto misled residents during the 2018 meeting, Surfside’s mayor told ABC News: “We’re going to have to find out.”

Meanwhile, Surfside officials and engineers are concerned that recent construction of a nearby residential building may have contributed to instability at the Champlain Towers South and, according to one expert, could have potentially been “the straw that broke the camel’s back.”

“Construction of a neighboring building can certainly impact the conditions, particularly the foundation for an existing building,” Ben Schafer, a structural engineering professor and director of the Ralph S. O’Connor Sustainable Energy Institute at Johns Hopkins University in Baltimore, told ABC News on Tuesday. “A critical flaw or damage must have already existed in the Champlain Towers, but neighboring new construction could be the ‘straw that broke the camel’s back’ in terms of a precipitating event.”

According to media reports from that time, the construction began in 2015 when Terra, a South Florida development firm, started erecting Eighty Seven Park, an 18-story luxury condominium in Miami Beach, across the street from the Champlain Towers South. The project caused such a raucous for residents that Mara Chouela, a board member of the Champlain Towers South Condo Association, reached out to Surfside officials in January 2019, according to records released by the town.

“We are concerned that the construction next to Surfside is too close,” Chouela wrote in an email. “The terra project on Collins and 87 are digging too close to our property and we have concerns regarding the structure of our building. We just wanted to know if any of tour officials could come by and check.”

Chouela received an email back from Prieto, saying: “There is nothing for me to check.”

“The best course of action is to have someone monitor the fence, pool and adjacent areas for damage or hire a consultant to monitor these areas as they are the closest to the construction,” Prieto added.

Surfside Commissioner Eliana Salzhauer told ABC News on Tuesday that Prieto’s response to Chouela reflects “laziness” from someone who was “too comfortable” in his job.

“The residents should have a place to go for their complaints,” Salzhauer said. “They should have been treated seriously.”

“What happened here is a wake-up call for every small town and for every government,” she added.

Residents and board members continued to complain about the project next door for several months, mostly about styrofoam and dirt from the construction site ending up on the Champlain Towers South pool deck and plaza, according to documents released by the town.

A spokesperson for 8701 Collins Development LLC, a joint venture that was established by Terra and other developers involved in the project, told ABC News in a statement Wednesday that they “are confident that the construction of 87 Park did not cause or contribute to the collapse that took place in Surfside on June 24, 2021.”

Jose “Pepe” Diaz, chairman of the Miami-Dade County Commission, told ABC News on Tuesday that he would not speculate what role neighboring construction had on the partial collapse but said officials will investigate it.

Lawsuits against the Champlain Towers South Condo Association have already been filed on behalf of residents, alleging the partial collapse could have been avoided and that the association knew or should have known about the structural damage.

A spokesperson for the Champlain Towers South Condo Association said they cannot comment on pending litigation but that their “focus remains on caring for our friends and neighbors during this difficult time.”

“We continue to work with city, state, and local officials in their search and recovery efforts, and to understand the causes of this tragedy,” the spokesperson told ABC News in a statement Monday. “Our profound thanks go out to all of emergency rescue personnel — professionals and volunteers alike — for their tireless efforts.”

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