Imran Yousuf, a bouncer at the Pulse nightclub, had an advantage. A Marine who had served in Afghanistan, Yousuf was able to use his training to quickly identify the impending threat and remain clear-headed as people died around him, according to the Marine Corps Times. Because of the 24-year-old’s decisive actions, he is being credited with saving dozens of lives.

AD

He told CBS News that he knew something was horribly wrong as soon as he heard the familiar crack of gunfire. It was then, he said, that his training took over.

“The initial one was three or four” shots, said Yousuf, a sergeant who left the Marine Corps last month. “That was a shock. Three or four shots go off, and you could tell it was a high-caliber [weapon]. Everyone froze. I’m here in the back, and I saw people start pouring into the back hallway, and they just sardine-pack everyone.”

AD

Yousuf told CBS that he knew there was a door behind the panicked crowd, but people were too overwhelmed to unlatch it.

“And I’m screaming, ‘Open the door! Open the door!’ ” Yousuf said. “And no one is moving because they are scared.”

AD

If they did not act, they could be targeted by the gunman, who could have appeared at any moment. They were a few feet from relative safety. Yousuf told CBS that there was “only one choice.”

“Either we all stay there and we all die, or I could take the chance of getting shot and saving everyone else, and I jumped over to open that latch and we got everyone that we can out of there.”

It was a simple act of heroism, but it may have been one of the most decisive actions that took place that morning. Asked how many people left through that exit, Yousuf told CBS that he estimated as many as 60 or 70.

AD

“As soon as people found that door was open, they kept pouring out, and after that we just ran,” he said.

Yousuf served in the Marine Corps from June 2010 to May 2016 as an engineer equipment electrical systems technician, according to service records obtained by The Washington Post. He deployed to Afghanistan in 2011 and most recently was assigned to the 3rd Marine Logistics Group.

AD

His military awards include the Navy and Marine Corps Achievement Medal, the Afghanistan Campaign Medal, the Korean Defense Service Medal and the Sea Service Deployment Ribbon.

Yousuf did not credit a particular type of training with steeling his nerves during the attack or helping him identify the rifle in close quarters.

During his general deployment time frame, Marines typically underwent pre-deployment training in Twentynine Palms, Calif., where they received what was known as Enhanced Mojave Viper training. The website MilitaryNewcomers.com described the experience as “the most realistic, live-fire training exercise in the Marine Corps.”

AD

“The units are presented with facilities, role players and scenarios that closely replicate the environment to which they will deploy,” the site said.

AD

During the same period, Marines training to deploy abroad were prepared for the possibility of an insider attack by Afghan forces. Such training may have borne some resemblance to the surprise attack in Orlando, although Yousuf hasn’t said as much. What he has said, according to the Times, is that he “just reacted.”

“There are a lot of people naming me a hero, and as a former Marine and Afghan veteran I honestly believe I reacted by instinct,” he wrote Monday on Facebook, according to the Times.

During his interview with CBS, he went a step further, wishing he could have done more during the attack. “I wish I could have saved more, to be honest,” he said. “There are a lot of people that are dead…. There are a lot of people that are dead.”

Dan Lamothe contributed to this report.