A 16-year-old boy from Victoria has been killed while participating in the Ride to Conquer Cancer.

Police said the fatal accident happened Sunday morning shortly after 10 a.m. in Arlington, Wash., just north of Seattle.

The boy, described as a “novice rider,” was reportedly riding with his mother and uncle in the cancer fundraiser when he attempted to pass a group of cyclists and fell onto the road.

“There was another oncoming car in the northbound lane, going well below the speed limit, but unfortunately she couldn’t stop in time,” said City of Arlington spokeswoman Kristin Banfield.

The driver of the oncoming car was unable to swerve out of the way and struck the teen, while hundreds of cyclists witnessed the gruesome collision.

“He was just lying face up, everyone, the paramedics had given up, and they’re just looking at him in horror, just like, ‘I can’t believe this happened,’” one rider told CTV News.

The driver of the vehicle, a woman in her 50s, is cooperating with police, officials said.

No charges are expected in what is being described as purely accidental.

The BC Cancer Foundation is now offering condolences and support to the victim’s family, who has asked for the boy’s name and details surrounding the incident to not be released, as well as privacy from the media.

“All who are associated with The Ride to Conquer Cancer have been deeply saddened by this news and our thoughts and prayers are with family and friends of the rider,” said president and CEO Doug Nelson.

“This has been an incredibly sad day for the BC Cancer Foundation, the Ride community and our supporters.”

The Ride to Conquer Cancer is a two-day event that sees thousands of cyclists riding from Vancouver to Seattle every year to raise money for cancer research.

Riders raised $10.4-million for the BC Cancer Foundation this year.

With a report from CTV British Columbia’s Julie Nolin and files from The Canadian Press