Seth Goldstein, 17, was halfway through the cross-country course when he saw a runner in front of him drop to the ground.
As other students continued to race, Goldstein stopped running and approached the runner in distress.
"His lips were turning blue and his eyes were rolled back in his head," Goldstein, a senior at Cooper Yeshiva High School in East Memphis, Nashville, told the Commercial Appeal. "I was terrified. But then I thought to myself, freaking out isn't going to help any here."
The student had bitten his tongue and was bleeding profusely.
Goldstein, who works part-time as a lifeguard, quickly motioned for a nearby parent to call 911. He then rolled the ailing student on his side so he wouldn't choke on his blood.
"Honestly, I was in shock," said Jessica Chandler, a mother of another runner. "But this guy was taking complete control. He was like, 'You — call 911. You — go get some ice.' He turned him on his side. I thought he was a parent or an EMT."
Goldstein remained calm and reassured panicked parents as he waited for paramedics to arrive. When the ambulance arrived, Goldstein asked paramedics if he could finish his race.
Goldstein finished the race — the slowest he's ever run, yet a self-described "personal best" — to the cheers of friends who long since crossed the finish line. Some even joined him for the last segment of the race.
"It's an example of exactly the values we're trying to instill in our kids," said Gil Perl, the dean of the Cooper Yeshiva School. "We have the concept, from the Talmud, that if you want God to have mercy on you, you have to have mercy on others."
Runner's World readers called Goldstein "world class," "a hero" and said that he brings "honour to our sport."
The fallen runner fully recovered. He had suffered a heat-induced seizure.