POLK COUNTY (Fox 13 WTVT) -- A Polk County family is mourning the death of a young Marine killed in an explosion at a training base in Nevada.
Lance Cpl. David Fenn of Polk City was among seven Marines who died Monday night during a training exercise. He was 20.
Fenn graduated from Auburndale High School, where he was in the ROTC. A family member told FOX 13's Ken Suarez that it was always Fenn's dream to be in the military. He joined the Marines right after high school.
"We're terribly saddened by the loss of David," Auburndale High principal John Hill said. "Just an outstanding, wonderful young man, and certainly our thoughts and prayers go out to his family, his friends and the community of Auburndale this morning."
Natasha Reimer, a senior at Auburndale High, said she found out through Facebook.
"He was a really good guy," she said. "I can't say he always tried to help. He was an ROTC guy, you know, pretty tough, but he was a really good guy and really good friend."
Marine investigators are still trying to figure out what caused a mortar shell to explode in its firing tube.
Last night, hundreds of people who live near the Hawthorne Army Depot came together to honor the Marines who died.
The Pentagon has halted the use of that type of mortar shell until an investigation can determine whether or not they're safe.
The Marines who died in the explosion were all based at Camp Lejeune in North Carolina.
Eight other service members were injured.