A Plum boy's death early Sunday while riding a bicycle has been ruled an accident by the Allegheny County medical examiner's office.

Wayne Zindel, 15, of Carnival Drive, and two friends who had been at his Holiday Park home for a sleep-over, went for a late night bicycle ride sometime before 1 a.m.

The boys were riding down a steep hill on Surfside Drive, which intersects Carnival. Wayne, who was riding a trail bike with no brakes, tried to turn onto Carnival toward home but lost control on gravel and skidded into a split rail fence, his friends said.

The two boys told police that Wayne struck the back of his head against the fence on the 500 block of Carnival, Allegheny County police said.

Plum police Lt. Jeffrey Armstrong said there was gravel on the pavement, though it had not been determined yesterday whether it contributed to the accident. The gravel may have been washed onto the roadway by recent rains, Lt. Armstrong said.

Paramedics attempted to resuscitate the boy at the scene before he was taken to Forbes Regional Hospital in Monroeville. He was pronounced dead at 1:56 a.m. at the hospital of head and neck injuries, the medical examiner reported.

County homicide detectives are investigating the accident.