Posted BY: RM | NwoReport

For 20 minutes back on Tuesday, May 5, 2015 the day he turned 17, Zack Clements was clinically dead.

Today he is alive with no apparent lasting effects from his ordeal.

But that’s not even the most amazing part of his story.

When he regained consciousness three days later at Children’s Medical Center in Fort Worth, Texas, Zack told his parents that he’d seen a man with a thick beard, blue eyes and long, ruffled hair, surrounded by angels.

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“I realized it was Jesus,” Zack, 17, of Brownwood, Texas, tells PEOPLE exclusively, taking a break from playing video games at home after his second day back at school since he was released from the hospital.

“He put his hand on my shoulder and told me that everything was going to be all right,” he says. “It made me feel like someone was watching over me and I was going to get through it. Since it happened, I feel like I’m a stronger person.”

The Clements were so astounded by Zack’s revelation that Teresa videotaped her son recalling what he saw.

“He said that he saw a line of angels and in the middle was the prettiest one of all – Jesus,” says Teresa, 39.

The family has been inundated with calls and comments – pro and con – since Zack went public with his revelation in a local TV interview.

“We’ve had people say he’s lying, or that we gave him a pill before school that day so it would look like he’d gone into cardiac arrest,” says Billy Clements, 40, who works for an oil-rig company.

“People can argue science and logic, but they can’t argue somebody’s personal experience,” he says. “They can’t take that away from Zack.”

A Miracle in the Making

Football endurance training had just started after school on May 5 when, with no warning, Zack collapsed on the Warriors’ football field next to several of his friends.

For 20 minutes, classmates, a coach and a paramedic crew performed CPR to revive him.

“The situation was one of the gravest I’d seen,” says Gary Bay, who is principal of the Christian high school and used to work on a volunteer ambulance crew.

“If everyone hadn’t worked on him as quickly and efficiently as they did, I’m not sure he would have made it,” he says.

Doctors told Zack’s parents that the prognosis was grim.

“For 20 minutes, he was legally dead,” Dr. Lisa Roten, 49, a cardiologist who helped care for Zack, confirms to PEOPLE.

“We were worried he may have suffered irreversible brain damage,” she says.

Once his heart resumed beating on its own, doctors put Zack into a medically induced coma, lowering his body temperature to help his brain recover from the trauma.

Roten and the rest of the medical team were astonished when Zack awakened several days later and was fully aware of his surroundings.

The teen’s heart failed, Roten says, due to a rhythm problem, inflammation and a slightly abnormal coronary artery.

“He is very lucky,” she says. “So often, people remain in a coma after something like this and don’t wake up.”

As for Zack’s Jesus story, Roten says she believes him.

“As a society, we don’t like to look at what’s going to happen to us after we die,” she says.

“It’s an uncomfortable thing,” she says. “But somebody who is not clinically dead or has not been in that state cannot say what Zack did or did not see. He is somebody who, for 20 minutes, didn’t have a heartbeat.”

A Grateful Family

Two and a half weeks later, the Clements are preparing to host a belated birthday party for Zack in June, with an open invitation to everyone who came together to save the lanky teen’s life.

“It’s a miracle – there’s no other word,” says Teresa, a receptionist.

“Everyone is just amazed that he made it,” she says. “His doctors told me they normally don’t work on people for that long. After a certain amount of time, if they don’t have a pulse, they call it.”

Now back to his normal school routine, except for sports (further tests will be needed before he gets clearance), Zack wears a defibrillator vest that will deliver a shock if it detects a life-threatening heart rhythm.

And Zack believes that what he saw during the 20 minutes he was clinically dead is one reason he’ll be able to blow out 17 candles on his birthday cake.

“I’m just really thankful to everybody who pulled together to help me that day,” he says.

“It’s kind of overwhelming,” he says. “I guess you could say that the whole experience has made me a more humble person. I’m happy to be here.”