• Omar Mateen is the suspect in the Orlando gay club shooting on June 12, Sunday.

Omar Mateen is the suspect in the Orlando gay club shooting on June 12, Sunday. (Photo : YouTube / BBC News)

The Orlando gay club shooting early morning of June 12, Sunday, has been described as the worst mass shooting in the United States history. The suspect, who pledged allegiance to the Islamic State or IS, has killed 50 and injured 53, making the mass shooting the worst in the U.S. since Sept. 11, 2001.

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The suspect has been identified as Omar Mateen, 29, of St. Lucie County, Florida. He was born in New York in 1986 with parents from Afghanistan. When he commenced shooting, he reportedly called 911 to pledge allegiance to IS, whose members cheered online with an announcement that called him an "IS fighter."

However, there is no evidence that the IS had directed or was aware of the attack before it was done. At a morning news conference, officials announced the death toll to be 50, which doubled what had been reported earlier.

Florida's Ninth District Rep. Alan Grayson called the attack "ideologically motivated" during the conference. Mayor Buddy Dyer of Orlando called June 12, Sunday, the "most difficult day" in the state's history at an afternoon news conference. Florida Gov. Rick Scott declared Orange Country, Florida in state of emergency to ensure whatever is needed by the city from the state would be immediately available.

Mateen was said to be organized and well-prepared and that he was not from the area. A police officer who works at Pulse Nightclub exchanged fire with him outside the club at 2:02 a.m., before the suspect entered.

Once inside, Mateen, who was armed with a handgun, assault rifle and "some kind of device," took hostages. There were about 320 people inside the premises.

The SWAT decided to rescue the hostages at about 5 a.m., and 11 Orlando police officers exchanged fire with the shooter. At 5:53 a.m., Orlando police announced on social media that the shooter was dead.

"This has nothing to do with religion," Mateen's father, Meddique Mir Mateen told NBC News. A few months ago, his son was angry when he saw two men kissing in Miami. The suspect's father thought that may be related to the attack.

Mateen's parents moved to New York from Afghanistan in the 1980s, according to NPR. The family was devoted to their children, a neighbor who wished not to be identified, told WNYC, the new site's member station.

The mass shooting was not connected to the shooting in Orlando on June 10, Friday, which killed "The Voice" alum Christina Grimmie. The suspect, Kevin James Loibl, 27, fatally shot himself after killing the singer.

Watch U.S. President Barack Obama laments on the Orlando gay club shooting.