An Orlando police officer working as private security at Pulse nightclub stopped Omar Mateen from killing more people by firing at him, which began a three-hour negotiation in which the shooter claimed to be wearing a bomb vest, according to Orlando Police Chief John Mina.

In this clip, Chief Mina explains why he decided to send the SWAT team into the club when he did.

#PulseShooting @ChiefJohnMina on what led to decision to breach walls of club and go in. #OrlandoUnited pic.twitter.com/CiPGgGXvsS

-- Orlando Police (@OrlandoPolice) June 13, 2016

The official number of club patrons killed by Mateen is 49, Mina said. The death toll of 50 reported Sunday included the shooter, he said. Another 53 people were taken to hospitals for treatment of wounds. All but one of the 49 victims have been identified, but just 24 of their families had been notified as of Monday morning, he said.

Watch the latest Orlando Police news conference via Periscope:

Sateen, who was armed with an AR-15 style rifle and a 9mm handgun, retreated to a bathroom after his exchange of gunfire with the officer. It was there that Mateen held several hostages, threatening to detonate a bomb unless unspecified demands were met, Mina said.

Guns traced in #Orlando shooting: .223 caliber AR type rifle and 9mm semiautomatic pistol. Similar to those pictured pic.twitter.com/Ao5pcLtwBg

-- ATF HQ (@ATFHQ) June 12, 2016

Police commanders decided to begin rescuing the hostages after abut three hours of talks be prevent more loss of life, the chief said. Mateen then emerged from the bathroom firing at SWAT officers, who fired back and killed him.

The officer who fired the fatal shot was himself hit in the head by a round from Mateen's gun, but his Kevlar helmut saved his life, Mina said.

Spoke with our officer, he is ok. We are glad he is alright and not seriously injured. Kevlar helmet saved his life. https://t.co/yHw1sGvosH

-- Chief John Mina (@ChiefJohnMina) June 13, 2016

Orlando Police shot down rumors that a second suspect in the club shooting is being sought.

Alert: Rumors of multiple shooters are unfounded. The one shooter, Omar Mateen, is dead #OrlandoUnited

-- Orlando Police (@OrlandoPolice) June 13, 2016

A federal prosecutor, however, did say investigators are looking at others who may have been connected to Mateen's attack.

"I do want to let you know that we have no reason to believe that anyone connected to this crime is placing the public in imminent danger at this time," U.S Attorney Lee Bentley told reporters Monday. "That there is an investigation of other persons. We're working as diligently as we can on that. We have teams of prosecutors, as well as teams of agents working around the clock, getting search warrants, getting court orders. If anyone else was involved in this crime, they will be prosecuted."

CNN is reporting that Mateen, who is a U.S. citizen born in New York of parents from Afghanistan, traveled to Saudi Arabia and the United Arab Emirates four years ago.

Breaking: #Orlando shooter traveled to #SaudiArabia & UAE in 2011-12, US official tells me pic.twitter.com/Oacilte0Ou

-- Jim Sciutto (@jimsciutto) June 13, 2016