DENVER — For so many of his friends, he was just Q-man — a superhero of sorts, a boy who lifted spirits and radiated cheer and charm.

And on Wednesday he was gone. Fifteen-year-old Quinton Sanford, a wrestler and cross country runner at Highlands Ranch High School, collapsed that afternoon during a school-sponsored run along the High Line Canal.

Friends said his father, who was present at the race, performed CPR, but Quinton died en route to the hospital.

For much of the school, Thursday was a day of mourning. Word of the sophomore’s death spread quickly.

Students came to school donning black, many crying throughout the day. Grief-stricken teachers couldn’t make it through class. The school already endured the loss of another student a few weeks ago.

A preliminary autopsy by the Arapahoe County coroner’s office was inconclusive. Additional test results are expected in eight to 10 weeks.

“If he just started talking to you, you would get a smile,” said 15-year-old sophomore Taylor Snow. “He was always happy, and he loved everyone.”