A Marine veteran who served in Afghanistan is being hailed as a hero for helping scores of people escape from an Orlando nightclub targeted by a terrorist .

When Imran Yousuf, a bouncer at the Pulse nightclub, heard the gunfire break out early Sunday morning , he told CBS News that recognized it immediately.

"You could just tell it was a high caliber," said Yousuf, a former sergeant who just left the Marine Corps last month. That's when his Marine Corps training kicked in, he said. He ran toward a locked door that people had huddled around, too terrified to move.

"I'm screaming 'Open the door! Open the door!'" Yousuf told CBS. "And no one is moving because they are scared.

" There was only one choice — either we all stay there and we all die, or I could take the chance, and I jumped over to open that latch and we got everyone that we can out of there."

By creating the exit, Yousuf estimated that about 70 people were able to get out of the nightclub safely . Forty-nine people were killed inside the nightclub and another 53 were injured. It was the worst mass shooting in U.S. history, and was carried out by a man who reportedly called 911 to pledge allegiance to the Islamic State group.

Imran Yousuf, a former sergeant, credited his quick response to his Marine Corps training. He told CBS News that when the shooting started, people inside the nightclub were so terrified that no one unlatched a door leading to safety.

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"I'm screaming 'Open the door! Open the door!'" Yousuf told CBS. "And no one is moving because they are scared. " he explained. "There was only one choice — either we all stay there and we all die, or I could take the chance, and I jumped over to open that latch and we got everyone that we can out of there."

By creating the an exit, Yousuf estimated that about up to 70 people were able to get out of the nightclub safely, he told CBS.

"I wish I could've saved more," he told CBS. "...There's a lot of people that are dead."

Yousuf served as an engineer equipment electrical systems technician in the Marine Corps from June 2010 to May 2016, according to service officials . He deployed to Afghanistan in 2011.

He was last assigned to 3rd Marine Logistics Group. His military awards include the Navy and Marine Corps Achievement Medal, Sea Service Deployment Ribbon, Korean Defense Service Medal and Afghanistan Campaign Medal.

Yousuf was not immediately available to comment on Tuesday morning. He posted a message on his Facebook page saying 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 on Monday. "I have lost a few of my friends that night which I am just finding out about right now and while it might seem that my actions are heroic I decided that the others around me needed to be saved as well and so I just reacted."

While he appreciates the support he has received, Yousuf stressed that people should focus on the victims' families, not him, he wrote.

"We need to show our love and profound efforts to the families and friends who have lost someone and help them cope with what happened and turn our efforts to those who truly need it," he wrote. "Once again I sincerely thank everyone and bless all those who are recovering and trying to make sense of it all."

Yousuf is one of several Marines who have saved lives in crisis situations. Marine veteran Nick Koahou played a major role in taking down two terrorists responsible for the December massacre in San Bernardino, California. On June 8, retired Master Sgt. Rodney Buentello lost his life while saving two teenagers from drowning in San Antonio.

Watch his full interview with CBS here: