UPDATED 10:48 p.m. ET

A gunman opened fire at a gay nightclub in Orlando, Fla. Saturday night, killing 50 people and sending 53 others to the hospital, according to the Orlando Sentinel. Police shot and killed the suspect, who has been identified by local officials as 29-year-old Omar Mateen, at the Pulse Orlando nightclub. The Sentinel reports that Mateen, the suspected lone gunman, called 911 shortly before the attack and pledged allegiance to the Islamic State.

The shooting began at approximately 2 a.m. EST, and then evolved into a hostage situation, according to NPR. Orange County Sheriff Jerry Demings said the shooting is being classified as a "domestic terror incident." Orlando Police Chief John Mina described what transpired:

"At approximately 0202 hours this morning, we had an officer working at Pulse nightclub, who responded to shots fired. Our officer engaged in a gun battle with that suspect. That suspect at some point went back inside the club, where more shots were fired. This did turn into a hostage situation. Obviously multiple officers from various agencies responded, SWAT team responded. At approximately 0500 hours this morning, the decision was made to rescue hostages that were in there." 

Mina said the suspect was "organized and well-prepared" and "appeared to be carrying a rifle—an assault-type rifle— and a handgun, and had some type of device on him," CNN reports. The New York Times reports that a handgun and an AR-15-type assault rifle were among the weapons recovered. The suspect's father has made a statement, saying, "We are apologizing for the whole incident." The suspect's father claims the shooting had nothing to do with religion, but could be related to the suspect's anger over seeing two men kissing in downtown Miami a couple of months ago.

The shooting at Pulse has been classified as the worst mass shooting in U.S. history, more deadly than the Virginia Tech shooting in 2007 that left 32 people dead the 2012 Sandy Hook Elementary School that left 27 people dead, according to CNN. The Los Angeles Times provides more context: 

Florida Gov. Rick Scott and has declared a state of emergency for the state, and Orlando Mayor Buddy Dyer has declared a state of emergency for the city, Fox 11 Los Angeles reports

Scott said the shooting is "an attack on all of us." 

After being contacted by several people inside the club during the hostage situation, police used explosives and an armored vehicle to blast through a wall of the club. A gun battle ensued and the shooter was killed. Mina said that at least 30 people were saved during the rescue mission. 

Pulse Orlando posted a status on the nightclub's Facebook page that said, "Everyone get out of pulse and keep running" after the shooting started.

FBI Assistant Special Agent In Charge Ronald Hopper said they have "suggestions that the individual might have leanings toward that ideology," when asked if the shooter had a connection to radical Islamic terrorism, although he did not provide any further details.

The shooter's ex-wife Sitora Yusufiy told the media during a press conference that he was unstable and bipolar, CNN reported. "He started abusing me physically, very often, and not allowing me to speak to my family, keeping me hostage from them," she said.

President Barack Obama addressed the nation, saying the shooting was an "act of terror and an act of hate." He also called the nightclub "more than a nightclub," saying it was also a "place of solidarity and empowerment."​

Presumptive Democratic presidential nominee Hillary Clinton also addressed the attack in a long post on her Facebook page.

Orlando police began to release the names of a handful of victims Sunday afternoon, and shared a website where names will be added as victims' families are notified.

The shooting at Pulse nightclub comes a day after singer Christina Grimmie was shot and killed at her concert in Orlando, although police don't see a connection between the two events. 

Note: This post has been updated throughout as information becomes available.

B3cTA0NDE6Z7kWkNoRoG4_fnnYetQsrc