(SURFSIDE, Fla.) — At least 18 people, including two children, have been confirmed dead and 145 others remain unaccounted for since a 12-story residential building partially collapsed in South Florida’s Miami-Dade County last week.

The partial collapse occurred around 1:15 a.m. on June 24 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. Since then, hundreds of first responders have been carefully combing through the pancaked pile of debris in hopes of finding survivors.

Meanwhile, 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 has 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.

The massive search and rescue operation, now in its ninth day, was temporarily halted for much of Thursday due to safety concerns regarding the structural integrity of the still-standing section of the building. Movement in the pile of rubble as well as in the remaining structure prompted the hours-long pause, according to Scott Nacheman, a structure specialist with the Federal Emergency Management Agency’s Urban Search and Rescue support team.

Structural engineers, who have been on site monitoring the situation to ensure the safety of rescue workers, are currently planning for the likely demolition of the rest of the condominium amid the ongoing search and rescue mission, according to Levine Cava. Nacheman, who is helping develop contingency plans for the demolition, told reporters it would be “weeks” before a “definitive timeline” is available.

The structure was cleared by crews last week, and all search and rescue resources have since been shifted to focusing on the pile of rubble. But the two sites are side-by-side and the remaining building has posed challenges for the rescuers trying to locate any survivors or human remains in the wreckage.

“Given our ongoing safety concerns about the integrity of the building, we’re continuing to restrict access to the collapse zone,” Levine Cava said during a press briefing in Surfside on Thursday evening.

Shortly after search and rescue efforts resumed Thursday evening, the Miami-Dade County mayor noted that the crews “looked really, really excited to get back out there.”

Heat, humidity, heavy rain, strong winds and lightning storms have also made the conditions difficult for rescuers, periodically forcing them to pause their round-the-clock efforts in recent days. Officials are monitoring weather systems in the region as the Atlantic hurricane season ramps up.

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.

President Joe Biden and first lady Jill Biden traveled to Surfside on Thursday to tour the scene of the disaster and meet with officials, first responders, search and rescue teams, as well as families of the victims. Recalling the 1972 car accident that killed his first wife and 1-year-old daughter as well as badly injured his two sons, Biden told reporters: “It’s bad enough to lose somebody but the hard part, the really hard part, is to not know whether they’ll survive or not.”

The cause of the partial collapse to a building that has withstood decades of hurricanes remains unknown and is under investigation by local and federal agencies. Built in the 1980s, the Champlain Towers South was up for its 40-year recertification and had been undergoing roof work — with more renovations planned — when it partially collapsed, according to officials.

A structural field survey report from October 2018, which was among hundreds of pages of public documents released by the town of Surfside 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.”

A slew of lawsuits against the Champlain Towers South Condo Association have already been filed on behalf of survivors and victims, 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 told ABC News they cannot comment on pending litigation but that their “focus remains on caring for our friends and neighbors during this difficult time.”

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