ORLANDO, Fla. (AP) — The Latest on the shooting at an Orlando nightclub (all times local):

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.

— Eric Tucker in Washington contributed.

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10:15 a.m.

Florida's governor is headed to Orlando after a shooting at a gay nightclub there left about 20 dead and 42 wounded.

Gov. Rick Scott says in a statement Sunday, hours after the incident, that thoughts and prayers are with the victims and their families.

The statement says he'll meet with law enforcement and local officials in Orlando.

Scott says: "We will devote every resource available to assist with the shooting in Orlando. Our state emergency operations center is also monitoring this tragic incident."

His statement also thanks the first responders.

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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9:45 a.m.

President Barack Obama has been briefed by his homeland security and counterterrorism adviser about the shooting at a gay nightclub in Orlando that left about 20 people dead and 42 wounded.

The White House said Sunday, several hours after the incident, that Obama has been briefed and has asked for regular updates as the FBI and other federal officials work with Orlando police on the case.

Press secretary Josh Earnest said in a statement that the president has directed federal officials to provide "any necessary assistance to pursue the investigation and support the community."

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7:25 a.m.

Police say approximately 20 people have been killed inside a Florida nightclub, and at least 42 were wounded.

Orlando Police Chief John Mina says authorities have not determined an exact number of people killed, but that "approximately 20" have died.

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

Mina says the shooter was armed with an assault-type rifle, a handgun and some type of suspicious device. Police had said previously on Twitter that there was a "controlled explosion" at the scene of the shooting at Pulse Orlando, a popular gay dance club. Mina says that noise was caused by a device intended to distract the shooter.

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7:15 a.m.

Police say multiple people have been killed inside a Florida nightclub, and at least 42 wounded people have been taken to hospitals.

Orlando Police Chief John Mina did not immediately provide an exact number of how many people were killed. Police had said previously that the shooting was a "mass casualty situation."

Mina says the shooter was armed with an assault-type rifle, a handgun and some type of device. Police had said previously on Twitter that there was a "controlled explosion" at the scene of the shooting at Pulse Orlando.

Mina also says the suspect had exchanged gunshots with an officer working at the club, then went back inside and took hostages around 2 a.m. About three hours later, a SWAT team made the decision to go inside and rescue the hostages. The shooter died in a gunfight with those officers.

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5:55 a.m.

Police say the person who opened fire inside a popular Florida nightclub is dead.

Orlando Police did not immediately provide further details on the department's official Twitter account on Sunday. It was not immediately clear how the shooter died. Police described the shooting as a "mass casualty situation" and said local, state and federal agencies were involved in the investigation.

It was not immediately clear how many people were wounded in the shooting, or if any of the victims had died. Police have told people to stay away from the area and said a noise in the vicinity was a "controlled explosion." No further details were provided on the explosion.

Dozens of emergency vehicles have swarmed the area around the club.

The club, Pulse Orlando, earlier posted on its own Facebook page just after 2 a.m.: "Everyone get out of pulse and keep running."

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5:15 a.m.

Police say a loud noise near the scene of a reported shooting at a nightclub in Florida was a "controlled explosion."

Orlando Police said on the department's official Twitter account Sunday that media should avoid "reporting inaccuracies." No further details were immediately provided about the explosion.

Police have said "multiple injuries" were reported following the incident at the Pulse Orlando nightclub near Orange and Kaley avenue. The department also advised people to stay away from area.

Multiple emergency vehicles have reportedly responded, including the Orlando Fire Department's bomb squad and hazardous material team.

Pulse Orlando earlier posted on its own Facebook page just after 2 a.m.: "Everyone get out of pulse and keep running."

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4:50 a.m.

Orlando Police say they are responding to a shooting at a nightclub in Florida.

A post on the department's official Twitter account early Sunday morning says "multiple injuries" have been reported following the incident at the Pulse Orlando nightclub near Orange and Kaley avenue. The department also advises people to stay away from area.

Multiple emergency vehicles have reportedly responded, including the Orlando Fire Department's bomb squad and hazardous material team.

Pulse Orlando earlier posted on its own Facebook page: "Everyone get out of pulse and keep running."

The incident follows the fatal shooting on Friday of 22-year-old singer Christina Grimmie, who was killed after her concert in Orlando by a 27-year-old Florida man who later killed himself. Grimmie was a YouTube sensation and former contestant on "The Voice."

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This story has been corrected to show that information about shooting being investigated as act of terrorism came from the Florida Department of Law Enforcement, not the FBI.