Friends identified the teenager as Kade Cooper, who finished his sophomore year at Layton High on Friday.

Cooper was participating in a 7-on-7 football tournament when he turned to his team's huddle and fell around 1:30 p.m., said Jeff Pledger, a spokesman for the Weber County Sheriff's Office.

Trainers performed CPR on the teenager but couldn't revive him, Pledger said. Cooper was transported to McKay-Dee Hospital Center in Ogden where he died.

Authorities were not aware of any pre-existing medical conditions that may have contributed to the teenager's death, Pledger said. The boy was described as "active" and "healthy," he said.

Layton High football coach Jim Batchelor said Cooper was drinking water and Gatorade throughout the afternoon. Cooper was playing in a tournament that featured roughly 75 teams from around Utah, Batchelor said.

The temperature at the time of the teenager's collapse was about 74 degrees Fahrenheit, Batchelor said. It's unclear whether warm weather played a role in the incident.

Cooper's death is under investigation, Pledger said. An autopsy is being conducted by the state Medical Examiner's Office.

Students gathered at the school's football field Saturday evening to grieve for Cooper, who Batchelor described as a "well-liked kid" with great athletic potential and a sharp mind in the classroom.

"He was a great kid that we had looked forward to coaching the next couple of years. He was having a great day, having the time of his life," Batchelor said.

"This whole thing is just shocking."

Cooper's friends stood with candles and signed cards during Saturday's memorial service.

Cooper played receiver and was also a member of the Lancer baseball team, Batchelor said.

The teenager also made an impact on his teachers in the classroom, said Scott Applegate, another football coach at Layton High School. Applegate taught Cooper in physical education and computer technology classes and was struck by Cooper's positive attitude in school, he said.

"He was a happy-go-lucky kid. He was a kid that always seemed to have a smile, very outgoing," Applegate said.

Cooper's teammates are taking his death hard, Applegate said.

"You don't like to see kids in this kind of pain. You don't like to see them have to deal with this," he said. mrogers@sltrib.com