Orlando Nightclub Shooting: Gunman Identified As Omar Mateen, More On Massacre That Left 50 Dead

UPDATE: The Islamic State's Amaq news agency said on Sunday that the Islamist militant group was responsible for the shooting, as reported by Reuters.

Early on Sunday, a gunman opened fire inside Pulse, a gay nightclub in Orlando, Florida, leaving 50 dead and over 50 others injured in what became the worst mass shooting in U.S. history.

As the venue was wrapping up its “Latin Night” party, the shooter, identified as 29-year-old Omar Mateen of Port St. Lucie, Florida, first exchanged fire with the police officer working as part of the club’s security, and then walked in minutes before 2 a.m. to take everyone inside as hostage.

At the moment of the incident, Pulse posted on its official Facebook page: “Everyone get out of Pulse and keep running.” And later on, around 6 a.m., they updated their status saying, “As soon as we have any information, we will update everyone. Please keep everyone in your prayers as we work through this tragic event. Thank you for your thoughts and love.”

State police and now government officials have classified the massacre a terrorist attack. Investigations are operating “under a theory that the Orlando nightclub mass shooting was inspired by Islamic State, the top Democrat on the House Intelligence Committee said Sunday,” the Orlando Sentinel reports. Orange County Sheriff Jerry Demings stated that he sees the incident that they should “certainly classify as domestic terror incident.”

Rep. Adam Schiff, D-Burbank also said in a statement that the similarities to the November attacks in Paris, specifically the one on the Bataclan, “indicate an ISIS-inspired act of terrorism.”

The tragic massacre comes only hours after "The Voice" season 6 finalist Christina Grimmie was shot to death by a 27-year-old man after one of her concerts. The man, identified as Kevin James, shot and killed the 22-year-old singer and shot himself after Grimmie's brother tackled him.