Police say the shooter at an Orlando nightclub used an AR-15-type assault rifle on all the victims.

Officials say 50 were killed at the popular gay club. That makes it the deadliest mass shooting in U.S. history.

Police Chief John Mina said at a Sunday news conference that the shooter used the assault rifle, with unknown rounds, and also had a handgun.

Officials at the news conference also say they have securing the suspect's vehicle, a van, right outside the club.

The shooter has been identified as Omar Mateen of Port St. Lucie, Florida. Officials have said they're investigating whether the massacre was an act of terrorism.

Dr. Mike Cheatham is a trauma surgeon at Orlando Regional Medical Center, where 46 patients were taken. The majority are in critical condition.

He tells The Associated Press, "I think we will see the death toll rise."

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10:50 a.m.

The massacre at an Orlando nightclub that claimed 50 lives is the worst mass shooting in U.S. history.

Police Chief John Mina confirmed at a news conference Sunday morning that 50 people were killed, up from 20 as earlier reported.

Mayor Buddy Dyer says 53 more are hospitalized after the early Sunday incident. He says the shooter is among the dead. He also says the shooter used an assault rifle on all those dead. Officials say one officer was shot, and has injuries to his face.

Earlier, U.S. Rep. Alan Grayson identified the shooter as Omar Mateen of Port St. Lucie, Florida. He cited law enforcement officials in speaking to reporters.

Officials also have said they're investigating whether the incident was an act of terrorism.

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10:30 a.m.

The mayor of Orlando says there were 50 casualties and there are 53 more hospitalized after a mass shooting at a popular gay nightclub there.

"There's blood everywhere," Mayor Buddy Dyer said Sunday at a news conference, hours after the shooting.

He says the shooter used an assault rifle on all those killed.

Earlier, U.S. Rep. Alan Grayson identified the shooter as Omar Mateen of Port St. Lucie, Florida. He cited law enforcement officials in speaking to reporters.

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10:20 a.m.

The suspect in the mass shooting at night club in Florida has been identified as Omar Mateen of Port St. Lucie, Florida.

U.S. Rep. Alan Grayson identified the shooter in the Sunday incident. He cited law enforcement officials in speaking to reporters.

A federal law enforcement official with knowledge of the investigation also identified him. The official was not authorized to discuss the investigation publicly and spoke on condition of anonymity.

Florida Department of Law Enforcement Special Agent in Charge Danny Banks said earlier that the mass shooting is being investigated as an act of terrorism. He says authorities are looking into whether the incident was an act of domestic or international terror, and if the shooter was a lone wolf.

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