"Shawn's always been a well-conditioned young man," Mahaffey said. "He always looked like he was chiseled out of rock."
Mahaffey said Shawn wasn't the biggest or most-talented player, but he approached the game with enthusiasm.
"He was one of those guys that just always showed up to practice with a smile on his face," Mahaffey said.
Shawn's 11th-grade English teacher, JoAnne Nave, said he quickly found his niche at Tech High after transferring from Boonsboro and had been looking forward to his senior year.
Nave described him as a "fine young man" who never spoke out of turn, but gave thoughtful answers when called upon and often volunteered to help out.
"If I had a problem with my computer or if I needed some books boxed, Shawn was the first one to ask if he could help," she said.
The Boonsboro High and Tech High communities were rocked by the tragedy as administrators called teachers with the news, Nave said.
"It's a tragedy anytime you lose anyone so young, but Shawn really was an outstanding young man," she said.
Shawn's 12-year-old brother, Ryan, "wanted to do everything his older brother was doing," Tammy Langley said.
Shawn helped Ryan set up his iPod with the boy's favorite songs, and the two played video games together.
Shawn and his best friend, Kevin Perkins, had known each other since second grade.
"They were almost blood brothers," Tammy Langley said.
The teenagers went hunting and skiing together, and often stayed at each other's houses.
Shawn, described by his mother as "very goal-oriented," was working as a service technician for Irrigation Unlimited in Frederick, Md., and worked at Reeders Memorial Home on weekends.
He loved to hunt deer and work on a 1968 Ford Mustang with his father, Tony Langley.
Shawn traded in a four-wheeler for an old Ford Ranger truck, which he and his dad fixed up, Tammy Langley said. Shawn was proud of that truck, which became his trademark around Boonsboro, she said.
Mahaffey said he knew Shawn's death would have an effect on the psyche of the tight-knit football team, but he didn't think Shawn would want them to dwell on it.
"He'd be wanting them to go out in the field and have some fun," he said.
The family will receive friends today from 1 to 3 p.m. and 6 to 8 p.m. at Bast-Stouffer Funeral Home in Boonsboro. Funeral services will be Friday at 11 a.m. at the funeral home.
Staff writer Heather Keels contributed to this story.