While on his rampage, Orlando, Fla., nightclub shooter Omar Mateen told 911 dispatchers that he was an "Islamic soldier" and threatened further violence by warning (falsely) that there were bombs in a car outside the club, USA Today reports.
"No, you already know what I did,'' Mateen said. "There is some vehicle outside that has some bombs, just to let you know. You people are gonna get it, and I'm gonna ignite it if they try to do anything stupid.''
The gunman also threatened to strap four explosive vests to hostages, Reuters reports.
According to USA Today, no explosives were found at the nightclub.
Mateen demanded that the U.S. "stop bombing Syria and Iraq," and also threatened more attacks in the coming days, the New York Times reports.
According to the Times, in calls to authorities that came between 2:48 a.m. and 3:24 a.m., Mateen spoke in Arabic, claiming responsibility for the massacre "in the name of God the merciful."
Mateen had three phone calls with law-enforcement authorities. He called 911 twice during the attack, and police called him back once. Mateen, according to USA Today, also made a "goodbye" call to a friend, called a television station and posted on Facebook while he carried out his massacre.
Of the 53 injured in the attack, 18 remained hospitalized Monday, USA Today reports, with four still in critical condition.
On Tuesday, Attorney General Loretta Lynch is scheduled to travel to Orlando to meet with families and also be briefed on the investigation. USA Today notes that Lynch stated that a key goal was to determine why Mateen targeted the LGBT community. Lynch declined, however, to say whether Mateen's wife, Noor Salman, who is accused of knowing about her husband's plans to attack the club, will be charged.