LITTLETON, Colo. -- A Littleton teen who was riding a skateboard while clinging to the side of a moving Jeep was killed Thursday morning when he lost control and fell off his skateboard, slamming into the car, police said.

John Nicolette, an 18-year-old senior at Heritage High School, was doing what is known as skitching -- hitching a ride with a vehicle, while you're on a bike or a board, as it is moving. The Jeep, which was packed with friends, was going southbound on South Windermere Street.

At one point, Nicolette lost control and flew off his skateboard near Meadowbrook Road. Nicolette suffered severe head trauma and was transported to Littleton Hospital, where he was pronounced dead at 9:48 a.m.

It's not known if he was wearing a helmet.

Students tell 7NEWS that boarders regularly have friends in cars tow them to the top of the hill so that they can ride back down. They don't usually wear helmets.

The driver was interviewed but was not arrested, Littleton police Lt Doug Parker said. There is no indication that drugs or alcohol were involved, police said. The driver's name has been released but 7NEWS is not disclosing his name because he has not been charged with a crime.

Nicolette's boarding buddies rode their skateboards by the accident scene as a tribute to him.

"It's just so sad because he was such a nice kid," said senior Christopher Beasley. "He just loved longboarding. He was the greatest person in the world. A nice kid. You really couldn't say anything wrong about him."

Thursday was supposed to be a day of celebration. It would have been Nicolette's last full day of school before graduation.

Heritage's annual assembly, where the school and its students say goodbye to graduating seniors, was canceled.

Staff at Heritage High School mobilized extra counselors Thursday morning to help students and family members cope with Nicolette's death.

"Springtime is an important time for seniors and it was a special day here today at this school, with the assembly. So they're taking it very hard," a school spokeswoman said.