ORLANDO: The gunman who massacred 49 people at the Pulse club in Orlando was himself a regular at the gay nightspot, four club goers told the Orlando Sentinel on Monday (June 13).

"Sometimes he would go over in the corner and sit and drink by himself, and other times he would get so drunk he was loud and belligerent," Ty Smith told the Sentinel, referring to slain shooter Omar Mateen, 29.

Smith told the paper that he saw Mateen inside at least a dozen times. "We didn't really talk to him a lot, but I remember him saying things about his dad at times," he said. "He told us he had a wife and child."

Another Pulse regular, Kevin West, told the Los Angeles Times that Mateen messaged him on and off for a year using a gay chat app.

And other clubgoers told local media and MSNBC that Mateen had been using multiple gay apps, including Grindr, with mutual acquaintances to "hook up".

Mateen also was at Walt Disney World in April, said a Disney manager who requested anonymity.

His wife Noor Zahi Salman was not cooperating with the authorities, according to a law enforcement official who spoke on the condition of anonymity, the Sentinel said.

Forty-nine people were killed and 53 others wounded in the attack, which was also the deadliest mass shooting in US history.

Federal Bureau of Investigation chief James Comey said his bureau was "highly confident" Mateen had been "radicalised" while consuming online propaganda and that he had claimed allegiance to Islamic State in Iraq and Syria (IS) leader Abu Bakr al-Baghdadi in a series of calls during the attack.