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.

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Image courtesy of Marine Corps