What we know about the Orlando mass shooting suspect Omar Mateen

ORLANDO, Fla. -- Omar Mateen called 911 to pledge his allegiance to ISIS after the shooting at an Orlando nightclub began, two separate law enforcement officials confirm to ABC News.

Some law enforcement sources had previously characterized Mateen as having sympathy for, or ties to Islamic terrorism.

Multiple law enforcement sources tell ABC News, Mateen was a U.S. born citizen who lived in St Lucie County, Florida. Mateen's parents were born in Afghanistan, officials said. He was born in New York City, but officials said there is no evidence he has been here recently.

He was believed to be living with his sister and her husband in Florida.

Mateen had two firearms licenses, a security officer license and a statewide firearms license, all expiring in September 2017.

Mateen's ex-wife, Sitora Yusufiy, originally from New Jersey, who now lives in Colorado. Sources said they met online eight years ago, got married in Florida, lived briefly in Fort Pierce, Florida and divorced in 2011. The marriage lasted only a few months before she left, sources said. She is now engaged to someone else in Colorado.

Yusufiy said Mateen showed no signs of radical beliefs while they were married. She said she divorced him after he became abusive.

"He was very short-tempered and he would often get into fights and arguments with his parents but because I guess was the only one in his life, most of the violence was toward me," Yusufiy said.

His father said he is "in shock like the whole country." He says he wasn't aware of anything his son might have been planning. Mir Seddique told NBC News that his son got angry when he saw two men kissing in Miami a couple of months ago and thinks that may be related to the shooting. He says it has nothing to do with religion.

Mateen took hostages and opened fire inside a crowded gay nightclub in Orlando, Florida, early Sunday morning, killing 50 people and wounding 53 others before SWAT officers killed him, authorities said.

Police Chief John Mina said Mateenhad an assault-style rifle, a handgun and a "suspicious device" with him during the attack.

Earlier, FBI assistant agent in charge of the agency's Tampa division, Ron Hopper, said investigators are "looking at all angles right now" to find a motive.

"We do have suggestions that that individual may have leanings towards that, that particular ideology (Islamic extremism). But right now we can't say definitively, so we're still running everything around," he said.

Mateen was well known to the FBI counter-terrorism squad. He was interviewed by agents three times over the last three years.

He allegedly told co-workers he had ties to know terrorists.

Authorities also say Mateen legally purchased at least two firearms within the past week or so. There were no criminal charges and nothing on his record that prevented from from the purchase.

Security company G4S said in a statement to the Palm Beach Post that he had been an employee of the company since September 10, 2007.

Information from ABC News and the Associated Press