VIDEO: Responding to the Orlando Nightclub Massacre

Mayhem and then a hail of gunfire. That is how Orlando police on Monday described how law enforcement had taken down Omar Mateen, the shooter who authories say killed 49 people and wounded 53 at the Pulse nightclub early Sunday morning.

Mateen—who police say opened fire at the club just after 2 a.m. with steady semi-automatic fire, raking the assembled of more than 350 dancing, drinking, and singing on Latin Night—had barricaded himself in a bathroom with a handful of hostages after trading fire with a uniformed off-duty officer at the club and first responders. After two hours of failed negotiation, Orlando Police Chief John Mina said he had no choice but to give the order to his SWAT team to breach the building, as time was running out to rescue the victims.

Mina said the off-duty officer engaged in a shoot-out with Mateen up until more officers arrived. Additional police officers arrived and also engaged the suspect, and “forced him to stop shooting and retreat to the bathroom where he had some hostages,” Time reports.

Believing loss of life was imminent, as Mateen threatened to use explosives, Mina said he gave the order to breach. An explosive breaching device was used, at about 5 a.m., but when that didn’t work police used an armored vehicle, known as a Bearcat. When officers were able to penetrate the wall, the police chief said “dozens and dozens” of people exited, including the gunman.

Officers and the gunmen then engaged in a brief, but intense gun battle, during which Mateen was killed and one officer was shot in his kevlar helmet, which stopped the round and saved his life.