PHILADELPHIA (CBS) — The athletic trainer for Upper Darby High School died after suffering a heart attack during Sunday’s Broad Street Run. The Upper Darby School District said in a statement that 25-year-old Brian Smart passed away.

Smart recently celebrated his birthday as he turned 25 on April 24.

“The youngest of seven doesn’t usually have an impact very often but he certainly did,” Brian’s father, Bill Smart, said.

Processing their loss, Smart’s mother and father are bewildered over the sudden passing of their youngest of seven sons.

The 25-year-old athletic trainer at Upper Darby High School appeared to be in peak health.

An avid runner, he completed a half-marathon and even past Broad Street Runs with ease.

“He was running just over eight-minute miles,” Bill Smart said.

But, he collapsed and died Sunday around mile eight of the 10-mile race, while running with his girlfriend, aunt, and two brothers.

“Preliminary on the autopsy is his heart is larger than normal, but there are a lot of tests that will take 10 to 12 weeks they said,” Smart explained.

Brian Smart had been at Upper Darby High School for less than a year but he was loved by the students he helped train.

“It is obvious that Brian was beloved by the students that he worked with, and we’ve been receiving messages all morning about his passing,” the school district said in a statement.

The school district also released a statement from Smart’s father, which reads, in part, “Thank you very much for such kind words and your prayers. The world certainly lost a good one yesterday … Brian really enjoyed working in UD, working with you and the students of Upper Darby.”

The superintendent of schools shared a picture sketched by a student that shows Brian Smart adorned with a halo.

“That’s the part I’m so proud of, that he connected with everyone,” Bill Smart said.  “Somebody out there was looking out for the things we were and Brian did just that.”

Brian Smart’s caring attitude, was especially felt by Nicole Sloan. Her son with special needs plays lacrosse and Smart kept a close eye on him making sure he stayed safe on the field.

“He was just really involved,” Sloan said.  “A really concerned guy. Really cared about the kids and the sport they were playing, and I never experienced that before.”

When asked about Smart’s legacy, his parents are most comforted by the big impact he had in the short time he spent doing the very job he loved.

“His sense of humor and his caring nature,” Brian’s mother said.

The school district says more information will be made available as it is known.

A change.org petition was already created to rename Upper Darby’s football stadium to Brian Smart Memorial Stadium.

“The athletic association at Upper Darby High School lost a member of their family on Sunday, May 5th. Brian Smart, the athletic trainer, passed away of a heart attack while running the Broad Street Run. He was loved by all of the athletes at the school. With the football stadium getting a turf field over the summer, we feel it would be an appropriate way to remember his legacy at Upper Darby,” the petition reads.

Philadelphia Mayor Jim Kenney and Broad Street Run race director Leo Dignam said in a statement that they are “deeply saddened by this tragic event.”

“The City of Philadelphia and Blue Cross Broad Street Run organizers extend our deepest sympathies to the family and friends of Brian Smart, a race participant who lost his life yesterday. We are deeply saddened by this tragic event, and our thoughts are with his loved ones,” the statement read.

Nearly 40,000 runners took part in Sunday’s 10-mile run.