A 12-year-old boy died after he accidentally hung himself on a zipline, according to the King County Sheriff's Office.

The boy was identified as Jackson Roos.

The accident happened when Roos was playing outside his home in the 8800 block of 255th Northeast just outside of Redmond Wednesday, said spokesperson Cindi West.

His mother thought he was riding his bike, but he was in the backyard on the zipline. After looking for him, she found him hanging on the zipline, West said.

Medics responded to the scene and attempted to resuscitate Roos but he was pronounced dead at the scene.

Detectives said the zip line appeared to be commercially made and installed.

"This is terrible," said West. "Our hearts go out to the family ... and the first responders that come here. This isn't something anybody wants to experience, whether you're a family member or police officer or firefighter so it's just tragic all the way around."

It's not known how the boy was caught up on the line. Detectives are investigating whether the helmet he was wearing was hung up or another line used to sit in while zip lining became entangled.

Jackson Roos is the second child to die from accidental strangulation in less than a month.

"The little girl from Sammamish that had a jump rope and somehow got strangled," said West. "These things don't happen intentionaly, they happen quickly and you know accidents happen."
Roos attended Evergreen Middle School. Counselors made an annoucement at the beginning of class Thursday and held a moment of silence. Students were encouraged to write messages of condolences on cards available throughout the school.