Louie Reyes was driving on the University of Maryland's campus Sunday when he heard screams.

"Someone call 911. We need a defibrillator. Does anyone have a defibrillator?"

A man had collapsed on the ground while dropping his son off for camp. He was in cardiac arrest.

Reyes pulled over, jumped out of his car, grabbed his personal AED, Automatic External Defibrillator, from the trunk of his SUV and went to work.

He hooked the device up to the semi-conscious man and it delivered a shock.

"Within seconds we had a pulse. Within 30 seconds he was breathing and talking. Within one minute he was asking, 'What's going on?" Reyes said.

The man is now improving at the hospital and thanked Reyes for what he did. Reyes has been credited for saving the man's life.

"I thought this only happens on TV," Reyes said.

Reyes said he had bought the AED for $1,300 at Costco to protect his 10-year-old son who is a catcher on a baseball team. He was concerned his son might need a shock from a defibrillator if he got hit in the chest with a fastball.

He thought he would never use it. Now, he says he hopes his story will inspire others to learn CPR and become familiar with AEDs.

"I will continue to carry one with me," he said.

"I was never interested in like health care and hearts but now that he's saved someone's life I think it's really special," said Reyes' daughter Bella.

Reyes hopes he never has to use it again but he feels good knowing it's there in his trunk just in case.