The man who gunned down 49 people in a gay nightclub in Orlando, Florida, last weekend called 911 during the attack, praising God and telling authorities, "I did the shootings" before hanging up, according to police transcripts.
Omar Mateen called 911 several times during the shooting, which also wounded dozens. Transcripts of the calls, which the FBI released on Monday, show the gunman claimed there was a vehicle with explosives in it outside the nightclub.
Mateen called the Orlando Police Department from the bathroom, where several people attempted to take cover after gunshots rang out in Pulse nightclub in the early hours of June 12. Faced with both an active shooter and a hostage situation, authorities for hours held off on confronting the suspect, attempting to still him with negotiation tactics.
Mateen spoke to police "in a chilling calm and deliberate manner," authorities said.
Once Mateen threatened to use explosives, however, police began an intervention. They rescued hostages through a hole in the club's wall and ultimately fatally shot the gunman.
Orlando Police Chief John Mina said he believes the hostage rescue attempts saved several people.
Only a small portion of the calls was made public. Some parts of the transcript, including a line about the shooter pledging allegiance to a person or group, are redacted.
An official told CNN previously that Mateen claimed to be affiliated with the so-called Islamic State group. He also reportedly made references to ISIS in a messages posted to Facebook during the attack.
House Speaker Paul Ryan (R-Wis.) said it was "preposterous" that the FBI had decided to keep most of the calls private.
"We know the shooter was a radical Islamist extremist inspired by ISIS," he said in a statement. "We also know he intentionally targeted the LGBT community. The administration should release the full, unredacted transcript so the public is clear-eyed about who did this, and why."
Authorities said they found no connection between Mateen and ISIS, and believe he was "radicalized domestically."
"He does not represent the religion of Islam, but a perverted view," Ronald Hopper, FBI assistant special agent in charge, said Monday at a press conference.
The FBI said it will not release 911 calls of any of the victims out of respect for their families.
UPDATE, 3:18 p.m.: The FBI released the transcripts in full on Monday afternoon, along with the following statement:
The purpose of releasing the partial transcript of the shooter's interaction with 911 operators was to provide transparency, while remaining sensitive to the interests of the surviving victims, their families, and the integrity of the ongoing investigation. We also did not want to provide the killer or terrorist organizations with a publicity platform for hateful propaganda. Unfortunately, the unreleased portions of the transcript that named the terrorist organizations and leaders have caused an unnecessary distraction from the hard work that the FBI and our law enforcement partners have been doing to investigate this heinous crime. As much of this information had been previously reported, we have re-issued the complete transcript to include these references in order to provide the highest level of transparency possible under the circumstances.