(COLLEYVILLE, Texas) — A Texas rabbi taken hostage with three members of his congregation by an armed man demanding the release of a convicted terrorist, posted a message on social media Sunday saying he is “grateful to be alive.”

Rabbi Charlie Cytron-Walker was leading Shabbat services at the Congregation Beth Israel in the Dallas-Fort Worth suburb of Colleyville, Texas, on Saturday when a man interrupted the service and allegedly claimed he had planted bombs in the synagogue, law enforcement officials said.

The suspect, who died in the incident when an FBI hostage rescue team breached the synagogue, was identified on Sunday as Malik Faisal Akram, 44, a British citizen, according to Matthew DeSarno, the special agent in charge of the bureau’s Dallas field office.

“At this time, there is no indication that other individuals are involved,” DeSarno said in a statement.

President Joe Biden said on Sunday that he was briefed on the incident by Attorney General Merrick Garland.

“This was an act of terror,” Biden told reporters.

Biden said the suspect had only been in the country for a couple of weeks, and spent at least one night in a homeless shelter. He said the suspect was armed with a gun he allegedly purchased on the street, but investigators have found no evidence that he was in possession of explosives.

The initial indication is that Akram was shot and killed by the hostage rescue team after it made what the FBI called the “deliberate decision” to breach the synagogue Saturday night to bring the standoff to an end, multiple law enforcement sources told ABC News.

After-action forensics will determine with certainty who fired the fatal shot and under what circumstances.

“All of us at the FBI are relieved the hostage situation in Colleyville, Texas, was resolved without physical injury to those taken hostage,” the FBI said in a statement Sunday. “We never lose sight of the threat extremists pose to the Jewish community and to other religious, racial, and ethnic groups. We have had a close and enduring relationship with the Jewish community for many years. We continue to work tirelessly with the Secure Community Network, the Anti-Defamation League, the Jewish Federation, and others to protect members of the Jewish community from all potential threats.”

The ordeal unfolded as members of Cytron-Walker’s flock watched in horror as a Facebook Live broadcast of the service suddenly turned into a life-threatening standoff that lasted 10 hours and ended with flashbangs and gunfire when an elite FBI hostage rescue team breached the temple and saved the hostages.

“I am grateful that we made it out. I am grateful to be alive,” Cytron-Walker wrote in a message posted on his Facebook page Sunday morning.

The cleric, affectionately known to his congregants as Rabbi Charlie, thanked friends and strangers from across the country for “all the vigils and prayers and love and support. He added a special thanks to the law enforcement officers and first responders “who cared for us.”

“I am grateful for my family,” Cytron-Walker wrote. “I am grateful for the CBI (Congregation Beth Israel) Community, the Jewish Community, the Human Community.”

Cytron-Walker released another statement Sunday afternoon saying active-shooter drills and security courses he and members of his congregation have taken from the Colleyville Police Department, the FBI and the Anti-Defamation League likely saved his life and the lives of the other hostages. He urged other Jewish congregations, religious groups and schools to get similar training.

“In the last hour of our hostage crisis, the gunman became increasingly belligerent and threatening,” Cytron-Walker said. “Without the instruction we received, we would not have been prepared to act and flee when the situation presented itself.”

The hostage-taking incident started about 10:40 a.m. on Saturday.

Olivia Zelling and Stacey Silverman said in an interview with ABC’s Good Morning America on Sunday that they were both watching the Facebook Live feed when the service went from prayer to panic.

Silverman said her mind was instantly flooded with fears that she was witnessing a repeat of the 2018 antisemitic mass shooting at the Tree of Life Synagogue in Pittsburgh and the deadly 2019 shooting at the Chabad of Poway synagogue near San Diego.

“I was terrified,” Silverman said.

While the livestream did not contain footage of the hostage-taking unfolding, it did include audio of the suspect apparently speaking to hostage negotiators. At one point, according to a portion of the broadcast obtained by the Fort Worth Star-Telegram, the suspect is heard saying, “I’ve got these prisoners” and “I am going to die.”

As Akram was allegedly speaking, the broadcast only showed a screen with written guidance on silent prayer and the words, “My God, guard my speech from evil and my lips from deception. Before those who slander me, I will hold my tongue; I will practice humility.”

“He was foul-mouthed. He was swearing. He was saying antisemitic tropes,” Silverman said of the suspect. “He was talking about Israel, Palestine, Islam, and that he had a gun. He implied he had a bomb in his backpack, and that he could, you know, let it loose at any minute. It was horrifying.”

Zelling said on GMA that she and her family are close friends of Cytron-Walker.

“Rabbi Charlie is at his core, an incredibly kind and holy man,” Zelling said. “His presence has made a profound impact on my life.”

Silverman said that while she has been alarmed about the rise in antisemitism and attacks on Jewish communities throughout the nation, she said, “in the back of our minds, you know, we knew it could happen here.”

“I feel like it’s going to take a long time for this congregation to heal, because you don’t know who next is going to approach your building,” Silverman said. “You don’t know what’s going to happen, because it’s so prevalent right now. We know that it could happen again. It’s terrifying.”

A motive for the incident is under investigation. The FBI’s Evidence Response Team was processing evidence at the synagogue on Sunday and the bureau’s North Texas Joint Terrorism Task Force, was investigating leads in the case, DeSarno said in his statement.

DeSarno said the FBI Shooting Incident Review Team “will conduct a thorough, factual, and objective investigation of the events.”

Assistant Chief Constable Dominic Scally of the Greater Manchester, England, Police Department, said British counterterrorism officers are assisting their U.S. counterparts in the investigation. Scally said in a statement that Akram was from the Blackburn area of Lancashire, about 20 miles northwest of Manchester.

“Police forces in the region will continue to liaise with their local communities, including the Jewish community, and will put in place any necessary measures to provide reassurance to them,” Scally said.

During the standoff, it was unclear to what extent the hostage-taker was armed, authorities said. The suspect was carrying backpacks and had said that he possessed explosives.

Authorities also declined to publicly confirm the demands made by the hostage-taker. Multiple law enforcement sources told ABC News he was demanding the release of convicted terrorist Aafia Siddiqui, who is incarcerated at Carswell Air Force Base near Fort Worth.

Siddiqui, a Pakistani neuroscientist with alleged ties to the al-Qaida terrorist network, was sentenced to 86 years in prison after she was convicted in 2010 of assault and attempted murder of a U.S. soldier and members of a U.S. team sent to interrogate her in 2008.

Investigators have not commented on the relationship between Siddiqui and the synagogue hostage-taker.

“For Congregation Beth Israel & the Jewish community, the immediate crisis is over. Yet the fear of rising antisemitism remains,” Secretary of Department of Homeland Security Alejandro Mayorkas said in a statement Sunday. “We must answer hate with action & ensure synagogues and all houses of worship are sanctuaries of safety, Shabbat and other days of faithful observance a time of peace, and America a place of freedom for all.”

ABC News’ Meredith Deliso, Aaron Katersky, Luke Barr and Josh Margolin contributed to this report.

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