The gunman who killed 49 people in an Orlando, Fla., nightclub was "cool and calm" during negotiations with police at the start of his bloody rampage, the hostage situation that followed and the police raid that ended the shootings early Sunday morning, according to the city's police chief.
But Omar Mateen "wasn't asking for a whole lot" during the roughly three-hour standoff, John Mina told reporters Monday morning. 
"We were doing most of the asking," he said. 
Mina and other officials confirmed Mateen, a U.S. citizen of Afghan descent from Port St. Lucie, Fla., called 911 during the standoff to pledge his allegiance to the Islamic State in Syria in Iraq (ISIS), and that the standoff persisted because Mateen had made threats about setting off bombs from inside Pulse nightclub. 
The standoff ended at about 5 a.m. ET when police attempted to blast a hole through a wall into one of the bathrooms and storm the club, Mina said. When the explosive charge failed to breach the wall, police punched through with an armoured car. Mateen was killed in the shootout that followed. 
Nightclub Shooting Florida
Orlando police Chief John Mina told media on Monday it was 'the right decision' to storm the nightclub, adding that the dozens of hostages still inside were believed to be in 'imminent danger.' (Chris O'Meara/Associated Press)

'Imminent danger'

Mina said it was "the right decision" to storm the club. He said the dozens of hostages still inside Pulse were believed to be in "imminent danger" because of a "timeline" Mateen had set with police. Mina did not elaborate. 
Fifty people, including Mateen, were killed. Another 53 were injured. 
Officials said Monday all but one of the victims have been identified, and roughly half of their families have been informed. 
Investigators also said a third weapon — apart from the handgun and assault-type rifle Mateen took into the club — had been found in his vehicle. 
Mateen had previously been investigated by the FBI for links to terrorism. He was first brought to the agency's attention in 2013 for making inflammatory comments to co-workers. In 2014, officials looked into ties between Mateen and an American suicide bomber, but found the contact was minimal and didn't constitute a threat.
APTOPIX Nightclub Shooting LGBT Reaction Seattle
Jeffrey Erikson and Jamie Fernandez hold each other during a moment of silence at a vigil in Cal Anderson Park in Seattle for the victims of the mass shooting. (Genna Martin/seattlepi.com/Associated Press)
The shooting on the weekend claimed more lives than any other by a single gunman in modern U.S. history. The previous most deadly shooting was the Virginia Tech killings, when 32 people were killed by a gunman in Blacksburg, Va., on April 16, 2007.
Mateen began shooting around 2 a.m. Sunday at the entrance to the predominantly LGBT club, which was welcoming guests for Latin Night on Saturday.
An officer working at the club exchanged gunfire with the suspect, who then went inside. 
There were about 300 people inside, and dozens were shot or caught in the hostage situation that followed. 
"He had an automatic rifle, so nobody stood a chance," Jackie Smith, who saw two friends next to her get shot, on Sunday. "I just tried to get out of there."