Orlando Gay Club Is Shattered In 'The Worst Mass Shooting' In U.S. History

Fifty people died -including the gunman- and another 53 were injured when a man opened fire and seized hostages at a gay nightclub in Orlando, Florida, early Sunday, making it the worst mass shooting in U.S. history, according to authorities. 

Authorities in Orlando started to release the namesof the first casualties of the deadly attack on The Pulse nightclub: Edward Sotomayor Jr., Stanley Almodovar III, Luis Omar Ocasio-Capo and Juan Ramon Guerrero. More names will be released in the next hours. 

President Barack Obama addressed the nation earlier Sunday afternoon and confirmed that the Federal Bureau of Investigation [FBI] "is investigating this as an act of terror". 

"This could have been any of our communities", said President Obama. "We will be there for the people of Orlando today, tomorrow and all the days to come."

Obama recognized that this is "a specially heartbreaking day for the LGBT community," and that " the place attacked was more than a nightclub. It was a place of solidarity and empowerment."

Hours before, Florida Gov. Rick Scott declared a state of emergency in Orange County (the Orlando area). 

"This is clearly an act of terrorism," said Scott. "It should make every American angry." 

"We have cleared the building, and it is with great sadness that I share we have not 20 but 50 casualties in addition to the shooter," Orlando Mayor Buddy Dyer told a news briefing, raising the death toll from 20 previously. "There are another 53 that are hospitalized."

Law enforcement have called the attack to The Pulse, a well known gay club in the area,  an act of terrorism. Dyer identified the shooter as Omar Mateen, a US citizen from Port St. Lucie, Florida.

Mateen, heavily armed, seized hostages early Sunday after shooting scores, eventually prompting a police SWAT team to storm the venue, officials said. At least one police officer was wounded in the raid, shot in the head, but saved by the Kevlar helmet he was wearing.

"This did turn into a hostage situation," Orlando police chief John Mina said. "At approximately 0500 hours this morning, the decision was made to rescue hostages that were in there."

FBI officials said the gunman may have extremist leanings — but it's too soon to know for certain. Mateen's family, however, seemed to suggest it was an anti-gay attack.

His father, Mir Seddique, told NBC News, "This has nothing to do with religion." Seddique said his son got angry when he saw two men kissing in Miami recently and thinks that may be related to the shooting.

"We are saying we are apologizing for the whole incident. We weren't aware of any action he is taking. We are in shock like the whole country," Seddique said to NBC News.

The shooter opened fire at Pulse at approximately 2 a.m. EDT  in an attack that later developed into a hostage situation. Mina described how the events unfolded:

Police were being contacted by people trapped inside the nightclub, he said, and "our biggest concern was future loss of life. We want to save those people."

"Everyone get out of pulse and keep running," Pulse Orlando posted to its Facebook page at 2:09 a.m.

Law enforcement used explosive devices and an armored vehicle to blast through a wall, Mina said, where a gun battle ensued with the suspect, ultimately killing him.

"There were at least 30 people who were saved during that rescue," he said.

Federal and local law enforcement said they were classifying the shooting as an incident of domestic terrorism.

Mina said it appears the shooter was "organized and well-prepared." He added that authorities were in the process of identifying victims and that it could take some time.

According to a search of public records, Mateen is 29 years old and listed as living in Port St. Lucie, Florida. The search shows that Mateen had a firearm license and he received a security officer license in both 2011 and 2013. The search did not turn up any criminal record.

Terry DeCarlo, head of the GLBT Center Of Central Florida, told reporter Catherine Welch of Orlando's WMFE that the group was opening crisis hotlines to help the LGBT community.

"We can't confirm — and I've talked extensively with the police department — that it was a direct hate crime against the LGBT community, it could have just been a person looking for a packed nightclub to go in and start shooting. We can't confirm that yet," he says. He adds that his main concern now is providing support for community members and their families.

The Human Rights Campaign said it had lowered its flag to half staff.

"This tragedy has occurred as our community celebrates pride, and now more than ever we must come together as a nation to affirm that love conquers hate," HRC President Chad Griffin said in a statement.

A statement from the White House said that President Obama has "directed that the federal government provide any assistance necessary to pursue the investigation and support the community." It added: "Our thoughts and prayers are with the families and loved ones of the victims."

Likewise, Florida's Gov. Scott said, "We are a strong and resilient state and we will devote every resource available to assist with the shooting in Orlando."

Sunday's horrific attack came a day after a gunman shot and killed singer Christina Grimmie at an Orlando concert venue, though police emphasized that they see no indication the two events are connected.

In Orlando, long lines developed from people looking to donate blood to help the victims; medical officials said there was a shortage of blood, especially type O and AB.

WMFE, NPR, Agence France Press contributed to this story. You can also read the Miami Herald's live coverage of the shooting here.