The suspected gunman behind a mass shooting at an Orlando nighclub has been identified as Port St. Lucie resident Omar Mateen, CBS News confirms.

Officials are still investigating the exact motives for the shooting, and both ties to radical Islam as well as a general hate crime motivation are being considered.

Sources have confirmed to CBS News that authorities are investigating whether the suspect had ties to Islamic terrorism. Police have said the attack appears to be an act of domestic terrorism, and officials are investigating whether the attack may have been inspired or directed by a terrorism group like ISIS or Al Qaeda, CBS News correspondent Jeff Pegues reports.

A U.S. intelligence source told CBS news senior investigative producer Pat Milton that Islamic terrorism is being investigated as a possible motive in the shooting because of several indicators, including the style of the attack, which had similarities to the attacks in Paris in November 2015 and Brussels in March. The gunman put up a protracted gun battle with police and was heavily armed, the source said.

Sources tell Milton that authorities investigating the incident are still looking into whether the attack is a hate crime.

Authorities are at the suspect’s home in Port St. Lucie and will likely comb through his computer and cell phone and attempt to hone in on his online footprint. They’re investigating whether he was on a terrorism watchlist, which could shed light on a possible motive, Pegues reports.

Mateen has no apparent criminal history, according to sources.

Orlando Police Chief John Mina said the suspect was found with a handgun and an AR-15-style assault rifle. Grayson said all the victims were killed with a single assault-style rifle and that the slaying happened “very quickly.” Officials are also processing a van they say was driven by the suspect.

There’s no current indication that Mateen had accomplices, police say.

The shooting and hostage situation early Sunday morning at Pulse — which describes itself as “Orlando’s hottest gay bar” — left at least 50 people dead, including the gunman, and more than 50 injured, officials say.

Florida Rep. Alan Grayson said Mateen was an American citizen, though he said he has several family members who aren’t. CBS News has confirmed that Mateen was born in the U.S., is 29 and has Afghan parents.

“I think it’s more likely than not it was an ideologically motivated attack,” Grayson said.

The suspect’s father has spoken out to the media, saying his son was anti-gay and he doesn’t believe the attack was motivated by religion.

The FBI says they haven’t determined whether the massacre was a hate crime, but Grayson said he believes “it’s no coincidence that the attack took place where it did and when it did.”

“It might be that we’ve seen the commission of an awful hate crime last night,” Grayson said.

Orlando Police Chief John Mina said an officer in full uniform was working extra duty at the club around 2 a.m. Sunday and heard reports of shots fired. He engaged the shooter, who went back inside the club and took hostages, Mina said. Clubgoers reported hearing multiple gunshots and fled amid a chaotic scene.

CBS News correspondent Jeff Pegues reports the suspect walked into the club heavily armed. He had an AR-15 style assault rifle and a handgun.

There was some concern initially that the gunman may have had a suspicious device, but investigators now believe that was not the case.

About three hours later, Mina said a decision was made to rescue the hostages, and officials say the suspect exchanged gunfire with a SWAT team. Law enforcement used flash-bang grenades and a SWAT vehicle to storm the building and may have saved the lives of nearly 30 being held hostage, CBS News reports. The suspected gunman was shot dead.

The attack is now the worst mass shooting in U.S. history.

Officials are trying to piece together a profile of who the suspect was. The FBI is leading the investigation and federal investigators are trying to determine who the suspect was in contact with in the days and hours leading up to the attack.