Mark Kindschuh, a Boston College student studying abroad in London, was enjoying his Saturday night with friends at a pub when chaos broke out just outside -- prompting the young man to jump into action.

Three men rammed a van into pedestrians on London Bridge and slashed and stabbed several people at nearby Borough Market before the police shot and killed them. The attack left seven other people dead, and dozens of people hurt.

WARNING: GRAPHIC IMAGES BELOW

Inside Wheatsheaf Pub in Borough Market, Kindschuh and other patrons quickly hid under tables in the back as dozens of people ran inside looking for safety.

NOTRE DAME HAMMER ATTACK SUSPECT YELLED 'IT'S FOR SYRIA'; INCIDENT INVESTIGATED AS TERROR

One gentleman, who the BBC reported appeared to be a Sheik man, collapsed near the 19-year-old Boston College student. Kindschuh didn’t hesitate to jump up and help.

“When I reflect on this, that point is when it went from lifesaving to life-sacrificing,” Kindschuh’s father, also named Mark, told Fox News on Tuesday. “There is a difference. When he made the decision – that is a different category of exceptional.”

“All I could see was one man at the front on the ground with a pool of blood forming,” the student told ABC News. “You couldn’t really see it, because there was so much blood around his head, but I searched around with my hands, and it was on the back of his head.”

He took off his belt and wrapped it around the man’s head trying to stop the bleeding. He then ran outside in hopes of getting more medical help, without knowing that police were about to take down one of the attackers.

When the younger Kindschuh went outside, police yelled at him to go back inside. Minutes later, one of the alleged attackers was shot down.

“He could see it happen,” his father recounted. “The situation was chaotic.”

The older Kindschuh, who runs the emergency department at Coney Island Hospital in New York, said he didn't believe his son was squeamish about blood or injuries, but never thought he would put his hands into the thick of it.

“The man is alive because he had the wherewithal to act,” Dr. Kindschuh said, adding that his son tried to go visit the man at the hospital on Tuesday, but was unable to get in.

The student is set to return stateside in the next couple of days.

Kindschuh is part of the ROTC, which means he will need to serve in the U.S. military upon graduation. His father said he had his doubts if his son would be capable in his duty, but his actions Saturday night changed it all.

KANSAS CITY POLICE OFFICERS DELIVER SURPRISE TO 3-YEAR-OLD ASPIRING COP

“I’m in a comfort zone now that he’s made the right choice and I don’t have any qualms of him serving in the military,” he said. “He has the ability to lead, for sacrifice and to not let his battalion down. I’m very good with it all.”

He added: “I understand my son more than I did before. Your 19-year-old is now a full grown man. I’m good. He’s not needy anymore in any way, shape or form. It’s beautiful just to learn that.”