(CNN) Former Army Maj. Richard Fierro never thought he would need to use the combat skills he learned in the military while on a night out with his family.
That's what happened Saturday as Fierro, his wife and daughter, his daughter's boyfriend and family friends were at Club Q in Colorado Springs, celebrating a birthday and watching a drag show.
Shots rang out at the LGBTQ nightclub just before midnight.
"I went to the ground as soon as I heard the rounds," said Fierro, whom President Joe Biden has called to thank for the heroism of what came next.
The veteran, who served three tours in Iraq and one in Afghanistan, said his training kicked in.
"I was in (fighting) mode. I was doing what I did down range. I trained for this," Fierro said Monday.
After hitting the ground, Fierro saw a man with a gun and jumped into action.
"I ran across the room ... pulled him down," he said.
Fierro and Thomas James were identified by police as two clubgoers who helped take down the suspected gunman. Five people were killed in the attack and 17 were wounded, officials say.
While hailed as a hero, Fierro told CNN it hurts to think about those who will never get to go home, as well as everyone in the building who was traumatized.
"This whole thing was a lot. My daughter and wife should've never experienced combat in Colorado Springs, and everybody in that building experienced combat that night -- not to their own accord, but because they were forced to," Fierro tearfully told CNN.
After the suspect was on the ground, another man -- apparently James -- helped Fierro subdue the gunman and pushed a rifle out of his reach.
That's when Fierro noticed the suspect also had a pistol, which Fierro said he took and used to hit the gunman.
"I found a crease between his armor and his head and I just started whaling away with his gun," he said. "I told him while I was hitting him, 'I'm going to f**king kill you, man, because you tried to kill my friends.' My family was in there. My little girl was in there."
While Fierro was hitting the suspect with a gun, the other man kicked him in the head. One of the drag performers also jumped in, Fierro said.
"She helped kick him with the high heels that she had on," he said.
As soon as the police arrived, Fierro said, he began tending to his injured friends.
"I don't want to ever do this," Fierro said of using his combat skills. "It lives in you. If you actually do this stuff, it's in you ... I'm not a GI Joe; I'm just a normal guy."
Biden called Fierro and his wife, Jessica, on Tuesday, White House spokesperson Karine Jean-Pierre said, explaining the president wanted to thank Fierro for his "courageous actions" and "instinct to act" in thwarting the attack and saving lives.
"He offered his condolences to them and also his support, and talked through what it's like to grieve. As you know, the president -- that is something that he is able to do very personally," she said. Biden in recent years has been outspoken on the grieving process he's endured since his first wife and 1-year-old daughter were killed in a 1972 car wreck and his adult son died in 2015 of cancer.
Fierro's daughter's boyfriend, 22-year-old Raymond Green Vance, was among those killed in the shooting, Fierro said.
"Raymond was a kind, selfless young adult with his entire life ahead of him. His closest friend describes him as gifted, one-of-a-kind and willing to go out of his way to help anyone," his family said in a statement.
The suspected gunman, identified as Anderson Lee Aldrich, remained hospitalized Monday. He is facing five counts of first-degree murder and five counts of a bias-motivated crime causing bodily injury, according to an online docket in El Paso County courts. El Paso County District Attorney Michael Allen, said formal charges have not been filed and the charges on the docket are preliminary and might change.
The League of United Latin American Citizens has announced a $5,000 reward for Fierro.
"Rich, who was twice honored with the Bronze Star for heroism in combat, exemplifies what our Latino servicemembers and veterans do in the face of danger, even when it means putting their own lives on the line," Domingo Garcia, president of the organization, said in a news release Tuesday.