At least 50 people are dead and more than 50 others wounded after a gunman opened fire and took hostages at a gay club in Orlando, Florida, early Sunday morning. This is the worst mass shooting in the history of the United States — began when the shooter - identified by several law enforcement sources as Omar Mateen, 29 - stormed the Pulse Nightclub about 2 a.m., with an AR-15 type rifle and a handgun, officials said.

Omar Mateen was born in New York in 1986 and was listed as living at a residence in Port St. Lucie, about 125 miles south of Orlando. Police said that he was shot dead about three hours later when a SWAT team entered the club. The incident is being investigated as an act of terrorism. Mir Seddique, Mateen's father, told NBC News more infos that help investigators :

" This has nothing to do with religion. A couple of months ago, my son got angry when he saw two men kissing in Miami, I think that may be related. 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. " - Mir Seddique, Omar Mateen's father

According to Florida records, Omar Mateen had active security officer and firearm licenses and worked in security. Three years ago, the FBI was looking into Mateen but the focus on the investigation wasn't on him, but rather on people he had been in contact with.

" We are shocked and saddened by the tragic event that occurred at the Orlando nightclub. We can confirm that Omar Mateen had been employed with G4S since September 10, 2007. We are cooperating fully with all law enforcement authorities, including the FBI, as they conduct their investigation. Our thoughts and prayers are with all of the friends, families and people affected by this unspeakable tragedy. " - Monica Lewman-Garcia, spokeswoman for G4S Secure Solutions

Police said Mateen was a U.S. citizen, but some of his family members are not. They would not say where those family members were from, and while they have not confirmed that Mateen was Muslim, several Muslim groups rebuked the attack as the Council on American-Islamic Relations Orlando Regional Coordinator Rasha Mubarak said in a statement :

" We condemn this monstrous attack and offer our heartfelt condolences to the families and loved ones of all those killed or injured. The Muslim community joins our fellow Americans in repudiating anyone or any group that would claim to justify or excuse such an appalling act of violence. " - Rasha Mubarak, American-Islamic Relations Orlando Regional Coordinator

The Pulse Nightclub later posted to Facebook. " Please keep everyone in your prayers as we work through this tragic event. Thank you for your thoughts and love. "

Following these events, President Barack Obama has addressed the nation from the White House to deliver a live statement :

" Dozens of innocent people were massacred, we support the people of Orlando. We know enough to say this was an act of terror and an act of hate. I just had a meeting with the FBI, all federal resources will be made available. We do not know the motives of this man, but he was a man filled with hate, we will try to find out why and how it happened. The killer has targeted a place of solidarity where people gather to better awareness of the homosexual community. Today is the deadliest shooting in the history of the United States. The people of Orlando will take all necessary assistance. We stand with the people of Orlando who have endured a terrible attack on their city, this could have been any one of our cities. It’s a sobering reminder that an attack on any American is an attack on all of us. " - President Barack Obama

Just last Thursday at an LGBT pride event at the White House, president Obama remarked on the “incredible ... violence” members of the LGBT community face around the world.

" We’ve got work to do when LGBT people around the world still face incredible isolation and poverty and persecution and violence, and even death," Obama said. "We have work to make sure that every single child, no matter who they are or where they come from or what they look like or how they live, feels welcomed and valued and loved. ” - President Barack Obama