At least 50 people were killed in a shooting at a gay nightclub in Orlando, Florida, making it one of the largest mass killings in America. WTSP
ORLANDO — A heavily armed assailant opened fire in a packed nightclub early Sunday, killing 50 people in the deadliest shooting spree in U.S. history before being fatally shot by police, local authorities said.
Mayor Buddy Dyer said 53 people were wounded at Pulse Orlando, a gay club just south of downtown. The FBI is investigating the massacre as a possible terror act link to radical Islamists.
A federal law enforcement official told USA TODAY the suspect has been identified as Omar Seddique Mateen of Port St. Lucie, Fla. The suspect's father, Mir Seddique, told NBC News on Sunday that he was "in shock," and that his son had recently expressed anti-gay sentiments.
Mulitple media outlets said Mateen is Muslim. His father said the attack "had nothing to do with religion."
Police Chief John Mina said the tragedy began at 2:02 a.m., when three police officers engaged the suspect in a gun battle outside the club. A hostage situation then took place inside, and a SWAT team was called in, Mina said. Police received updates from patrons trapped in the club, and decided to storm the club at about 5 a.m.
"Our biggest concern was further loss of life," Mina said. "We exchanged gunfire with the suspect, and he was dead at the scene."
Mina initially estimated the death toll at more than 20 people. Hours later the true scale of the horror was revealed. Mina said one officer was wounded and at least 30 people were rescued.
"Tonight our community witnessed a horrific crime... that will have a lasting effect on our community," a solemn Dyer said.
FBI Special Agent Ronald Hopper said the case was being investigated as a possible act of terrorism, either domestic or international. It was not clear if the shooter acted alone, he said, adding that authorities were trying to determine if there was a connection with radical Islam.
"We do have suggestions that the individual may have leanings toward that particular ideology," Hopper said.
The federal law enforcement official said investigators were reviewing the attacker’s possible utterances to determine if he had a terrorist ideology or affiliation. The official, who did not want to be named because of the sensitivity of discussing such information, characterized the attack as “certainly’’ terrorism. It was not immediately clear whether investigators were aware of the attacker prior to the assault.
Investigators were interviewing members of Mateen’s family Sunday in an attempt to learn what may have prompted the assault, the official said. The official told USA TODAY that investigators are reviewing a range of possible motivations and Mateen’s recent travels and contacts to learn more about possible preparations for the attack.
Gov. Rick Scott declared a state of emergency for Orange County.
"You don't want this to happen anywhere in the world," Scott said. "It's devastating when you see how many people lost their lives and the impact on the families."

Muhammad Musri, president of the Islamic Society of Central Florida, thanked law enforcement officials for their efforts and cautioned against any rush to judgment.
"No one could have expected this, no one could have prepared for it, it could have happened anywhere," a visibly shaken Musri said at a news conference. "It's like lightening."
He said the city and Muslim community "are heartbroken."
Mina said the gunman was armed with an assault rifle, a handgun and some sort of unidentified device. Officers from multiple agencies and dozens of emergency vehicles responded to the scene. Orange County Fire and Rescue called for gurneys to move victims from the club.
Many of the casualties were rushed to Orlando Regional Medical Center, which was placed on lockdown. The process of identifying the victims and notifying families was underway.
Jose Honorato was desperately awaiting news about his brother Miguel, 30, who was at the club with three friends. The friends made it out OK, but Jose said he had no idea if Miguel was at the hospital or was one of the bodies lying dead in the club.

"My brother's wife called me looking for him after she heard the news," he said. "I called his cell phone and he would not answer."
President Obama expressed his condolences to all the families and loved ones involved. The White House said Obama was getting updates on the case from Homeland Security.
Information on the tragedy slowly was revealed through the early morning hours.
"We can confirm this is a mass casualty situation. Support from local/state/federal agencies," Orlando police tweeted about four hours after the initial gunfight. Then, a short time later: "Pulse Shooting: The shooter inside the club is dead."
Mina said there was no indication that there was more than one shooter. A bomb squad was at the scene, and police reported conducting a "controlled explosion."
Hours after the shooting, police were still trying to piece together what happened.
"Anyone who was at Pulse nightclub and was a witness please come to the Orlando Police HQ," the department tweeted. "Any information you have could aid investigators in this case."
FBI Director James Comey has said that authorities have about 1,000 open investigations into homegrown violent extremists, the overwhelming majority with alleged ties to the Islamic State, the extremist group that has seized territory in Syria, Iraq and Libya.
June is Gay Pride month across the nation, and Orlando recently wrapped up its annual week-long Gay Days festival. Up to 150,000 in the LGBT community attended area theme parks, gay nightclubs and special events. It remains one of the largest gay pride events in the world.
Saturday night into Sunday the club was celebrating Latin Night. Club patron Christopher Hansen told CNN he heard what could have been 20 or 30 shots, setting off a panic as people scrambled for cover or raced for the exits. He said he helped a couple people who were wounded.
"It's just shocking," said Hansen, who crawled to safety. "I just saw bodies going down."
As the tragedy was unfolding, Pulse Orlando posted to its Facebook page: "Everyone get out of Pulse and keep running."

As soon as we have any information we will update everyone. Please keep everyone in your prayers as we work... 
Ali Kurnaz, 25, told USA TODAY he was working in his living room about a block from the nightclub when he heard gunfire.
"I could hear multiple rounds of gunfire to the point where it scared my cats," Kurnaz said. "They came running from a different room."
Kurnaz said he heard sirens as multiple police cars headed to the crime scene and helicopters flying over his neighborhood.
In some tweets appearing to come from inside Pulse nightclub short after the assault, people said they were hiding. Twitter users also said they heard multiple gunshots.
The shooting spree came just one day after The Voice star Christina Grimmie was shot and killed after a concert Friday night at the Plaza Live Theater in Orlando. That gunman, identified as Kevin James Loibl, 27, of St. Petersburg, Fla., fatally shot himself after the attack.
Bacon reported from McLean, Va. Contributing: Steph Solis, Chris Bonanno, Carolyn McAtee Cerbin,Kevin Johnson, Doug Stanglin and Jennifer Sangalang, USA TODAY Network