Mir Seddique said Sunday morning that his son, 29-year-old father and husband Omar Mateen, was not motivated by religion.
However, as the death toll jumped from 20 to 50, making this the deadliest mass shooting in American history, Seddique told NBC that his son became enraged weeks earlier during a trip to Miami.
“We were in downtown Miami," Seddique said. “He saw two men kissing each other in front of his wife and kids and he got very angry. They were kissing each other and touching each other and he said, ‘Look at that. In front of my son they are doing that.’ And then we were in the men’s bathroom and men were kissing each other.”
Seddique was speaking to reporters to apologize on behalf of his family and disavow his son's actions.
Police say Mateen, a security guard in the Port St. Lucie area, was first engaged by a cop outside the Pulse nightclub.
Mateen was believed to have had an AR-15 style assault rifle as well as a handgun. A standoff with police lasted three hours.
About 30 people were saved when a SWAT armored vehicle smashed through one of the club's walls.
The event has been classified as an act of domestic terrorism, the worst on American soil since September 11, 2001.
While Sen. Bill Nelson addressed reporters during a press event in Florida, he revealed that Mateen possibly had connections to ISIS.
Authorities began searching Mateen's St. Lucie area home Sunday morning.
"Appreciate the congrats for being right on radical Islamic terrorism," he wrote. "I don't want congrats, I want toughness & vigilance. We must be smart!"
It sparked a flurry of anger on the social network, with other users accusing the presidential hopeful of being tone deaf.
"Trump is a truly awful person," singer John Legend wrote as he quoted Trump's tweet.
"Once again, Donald, you have shown why you cannot lead us," George Takei wrote. "50 people are dead, and you bask in congratulations."
Senator John McCain's daughter, Meghan, asked: "You're congratulating yourself because 50 people are dead this morning in a horrific tragedy?"
At least 50 people were killed in the deadliest mass shooting in American history, and another 53 were injured, when suspected gunman Omar Mateen, 29, attacked Pulse in Orlando in the early hours of Sunday.
The Orlando gunman pledged allegiance to the Islamic State during a 911 call he made during the attack that left 50 dead so far, officials said.
According to reports, Omar Mateen also referenced the Boston Marathon bombings in the phone call he made to emergency dispatchers after 2 a.m. on Sunday.
Officials told CNN the 911 call was made some 20 minutes into the attack on Pulse, an Orlando gay nightclub.
The ex wife of suspected Orlando gay bar shooter Omar Mateen claims her former spouse beat her during their relationship.
In an interview with the Washington Post in which she remains anonymous, the woman said Mateen was violent and emotionally unstable.
The 29-year-old died Sunday morning after police believe he killed at least 50 people during an early morning assault rifle attack at Pulse nightclub.
“He was not a stable person,” the ex-wife told the Post. “He beat me. He would just come home and start beating me up because the laundry wasn’t finished or something like that.”
The attack is being called the worst ever mass shooting in America's long history of gun violence.
The ex wife, who spoke on the condition of anonymity out of fear for her personal safety, said she married Mateen about eight years ago after meeting him online.
When they first met, “he seemed like a normal human being,” the woman said.
However, after she said violence became the norm in the home, the woman's family flew to Florida to help her get out of their Fort Pierce home.
The woman said she fled with none of her possessions. She said, in the wake of the attack Sunday, that she feels lucky to be alive.
- Developing stories via INSIDE EDITION