(Updated at 7:55 p.m.) John Malvar, an 18-year-old Arlington high school student, died after a skateboarding accident in Arlington Heights this afternoon.

The accident happened on the 300 block of S. Highland Street around 12:30 p.m. According to police, Malvar was skateboarding down the street while hanging on to the side of a pickup truck, driven by a 17-year-old male student at an unknown rate of speed.

Malvar somehow lost his balance and fell to the ground, hitting his head. He was not wearing a helmet. The fall caused “significant head trauma” and left a large pool of blood on the ground.

The teen was in cardiac arrest when paramedics arrived on scene, according to Arlington County Police spokesman Dustin Sternbeck. Medics performed CPR, Malvar regained a pulse, and he was rushed to George Washington University in critical condition, Sternbeck said. He was later pronounced dead.

Charges — reckless driving, most likely — are pending against the 17-year-old driver, according to Sternbeck. Malvar and the driver attend both Washington-Lee High School and the Arlington Career Center, according to Arlington Public Schools spokesman Frank Bellavia.

Malvar attended his senior prom last week, posting photos of himself and his date on Instagram (right). Washington-Lee High School’s graduation is set for June 20.

The 300 block of S. Highland Street was closed for several hours while crime scene investigators took photos and measurements of the accident scene. Detectives also interviewed witnesses and canvassed the street to see if any video surveillance systems might have recorded the moments prior to the accident.

Via Twitter, Washington-Lee Principal Gregg Robertson called Malvar “an awesome kid” who was proud of his perfect attendance this year. Robertson sent the following email to parents late this afternoon.