WORCESTER (CBS) – A 71-year-old Middleton man is alive thanks to the skill and kindness of a stranger.

“I probably don’t fully realize how close to death I came,” Joe Flak said.

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Flak was at Shrewsbury High School Sunday watching a gymnastics meet when he collapsed while talking with a friend.

“In the middle of the conversation, mid-sentence, he said I just went down like a fallen timber,” said Flak. “He didn’t know if I had a heart attack or a stroke. Didn’t know if I was dead or alive.”

Luckily for Joe, Riley Olander saw what happened and ran to get her mom who was also at the meet. “I said ‘there’s a man on the ground upstairs, everybody’s panicking for a nurse,’” Riley said.

Amy O’Connor and Joe Flak and Riley Olander (WBZ-TV)

Amy O’Connor is a nurse at UMass Medical Center in the pediatric ICU.

“Joe was on his side not responding, not moving,” O’Connor said. “So I put him onto his back and I checked his pulses and he had no pulse.”

“She immediately runs upstairs, breaks through the crowd, starts pounding on my chest, it’s still sore today, my chest is still sore,” Flak said.

“But you’re here,” O’Connor said.

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“I’m here,” Flak said.

Amy O’Connor and Joe Flak (WBZ-TV)

Amy performed CPR for about ten minutes before Joe’s pulse came back.

“Anything could have happened you know, you think of the brain, you think of all the vital organs that might not have been getting oxygen,” O’Connor said.

“This is the first I’ve heard the full story and I’m amazed how lucky I am,” Flak said.

Joe is feeling good, but doctors are still trying to figure out what caused him to collapse.

“They have ruled out a heart attack and they have ruled out a stroke,” Flak said.

“The cool thing was seeing him sitting up on the stretcher and talking in the emergency room,” O’Connor said.

“There’s good people in the world, that’s the bottom line,” Flak said. “There’s still good people in the world.”

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This is the third time in the last year that off-duty nurses from UMass Medical saved people’s lives in emergency situations.