Students comfort each other at the site of the fatal crash that killed Shawn Gangloff, 15, who attended Montgomery County’s Sherwood High School. The driver and another passenger, both 17, were seriously wounded. (Michael S. Williamson/The Washington Post)

They had just finished the first week of school, it was the start of Labor Day weekend and a group of high school friends was hanging out at a home in Olney around midnight Friday. When Nick Stull decided to leave, he asked Shawn Gangloff if he wanted to go with him.

Gangloff opted to stay at the gathering, getting a ride with some other friends that ended, shortly before 1:30 a.m., on a dark road, with the car hitting a tree, a light pole and a telephone box before flipping over. Gangloff was ejected. The easygoing 15-year-old who loved lacrosse and Hacky Sack, drawing, skiing and skateboarding, died the next day.

The 17-year-old driver and a 17-year-old passenger — like Gangloff, students at Sherwood High School in Montgomery County — were trapped in the front of the silver Chrysler convertible and were hospitalized with serious injuries.

Like many in Olney, a close-knit small town in a county that has suffered through a series of fatal crashes involving teen drivers in recent years, Nick was struggling with disbelief Sunday. “He shouldn’t have died,” the 16-year-old said. “It could have been avoided if I had convinced him to leave. I could have tried harder.”

With school milestones and celebrations, it’s something that happens all too often and is always heartbreaking: young people in a car late at night, a missed turn, a horrible crash. Before dawn and through the long weekend in Olney, news, rumors, moments of hope, prayers, memories, fear and grief flicked from phone to phone via Twitter, text, Snapchat, Instagram.

Nick and two friends gathered at the roadside memorial to Shawn at the crash site Monday afternoon, what was supposed to be the end of a fun, late-summer-long weekend. Throughout the day, cars pulled over and people paused at the corner of Hines Road and Macduff Avenue to share their grief.

More than two dozen bouquets ringed the base of the tree and three lacrosse sticks rested against it. There was a teddy bear, a Sherwood T-shirt, a smiley-faced balloon. Someone tacked up a poster of Shawn with his photograph — smiling, his tongue out. Friends scrawled messages:

“Keep smiling.”

“Rest easy warrior.”

“You brought joy to everyone.”

And a typewritten note: “Know that if [the driver] could switch places with you he would in a heartbeat. Six feet under the ground but always in our hearts.”

A boy kissed his fingers and touched Shawn’s photo.

Two girls held each other and wailed.

“He just really enjoyed making people happy around him,” one 17-year-old student said.

Some parents brought their teenagers, both to say goodbye to a friend and to warn their children: Look how easy it is to lose it all.

People gathered at prayer sessions for all three boys.

Friends spending the afternoon at the hospital planned to paint a skateboard for Shawn and nail it to the tree Monday night. Some decided to gather at the McDonald’s in the center of town where he loved to hang out, They walked from there to the makeshift memorial.

In nearby Gaithersburg, members of a community group formed in the wake of another high school car accident marched in a Labor Day parade wearing Sherwood colors.

“It’s heartbreaking,” said Patty Winters, whose daughter graduated from Magruder High School, where three young alumni were killed in a 2011 car accident .

Earlier this year, a 16-year-old girl was killed in Gaithersburg when two cars driven by Magruder students crashed and one careened onto the sidewalk where she was walking.

Police don’t know yet what caused the crash in Olney early Saturday morning. They said they are investigating.

Sherwood High School Principal William Gregory said counselors will be available at the school Tuesday, and schools officials asked everyone to wear Sherwood gear as a show of solidarity.

“Sherwood is a very tight community. We reach out to take care of one another, inside and outside the school,” Gregory said. “This tragedy has devastated us.”

The father of the driver of the car said the family is deeply saddened and is grieving.

“Our hearts and prayers go out to the family and community involved, the boy still in the hospital right now and, most importantly, to the family that lost their son,” the father said. “We ask everyone to keep them in their prayers. . . . Everyone is pretty much hurting. and this is a time for everyone to focus more on healing.”

The Washington Post generally does not identify minors injured in car crashes, and no one has been charged in connection with Saturday’s crash. Attempts to reach the family of the other passenger were unsuccessful.

Shawn’s mother, Allison Gangloff, a fifth-grade teacher at Olney Elementary School, said at the door to the family’s split-level brick home that her son was “a great kid, kind and special.” Her voice trembled momentarily.

“We don’t know any of the details of what happened,” said Rick Gangloff, who teaches auto mechanics at Edison High School.

Shawn’s birthday was later this month, and he had planned to get up early on Saturday to try to get tickets to a sneaker release party for a new brand. He had hoped to go to Salisbury University, on Maryland’s Eastern Shore.

Joseph Stull, Nick’s father, said he felt sorry for everyone involved. He worries about his son’s driving. “I think all parents worry about that. Nick’s a good driver, but good drivers have accidents, too,” he said.

“I think all parents in the community share in that loss,” Stull said. “It’s a very tragic thing.”

He didn’t have to die, Nick said. The gathering at a friend’s house was so close to where Shawn lived, just half a mile away. So close that Shawn could have walked home.

Donna St. George, Dan Morse and Michael S. Rosenwald contributed to this report.