The tone of the worst mass shooter in American history ranges from calm to nervous to irritated in a series of 911 calls released by police Monday. In the calls, Orlando gunman Omar Mateen, who called 911 from inside the Pulse nightclub, can be heard pledging allegiance to ISIS, calling himself an Islamic soldier, and describing the massacre as revenge for American bombing in Iraq and Syria, CBS reports. He hung up on police several times. A negotiator who identifies himself as Andy deals calmly and professionally with Mateen, though during one attempt to call him back, Andy tells fellow officers that he's not convinced the man he's dealing with is really inside the nightclub, the Orlando Sentinel reports.
Mateen becomes impatient as the negotiator tries to obtain information, telling him it's "none of his business" whether he has an accomplice. At one point, he claims to have vehicles full of bombs outside the nightclub. "Your people are going to get it and I’m going to ignite it if they try to do anything stupid," says Mateen, who was shot dead by police at the end of an attack that killed 49 people and injured 53 others. The AP reports that audio of the calls was released by order of Circuit Judge Margaret Schreiber, who is still considering whether to release another 232 calls to 911 made during the incident. The city of Orlando's lawyers say they shouldn't be made public because they involve suffering and killing. (Read more Omar Mateen stories.)