EL JEBEL, Colo. -- Investigators have concluded that a 10-year-old boy who died at a skateboard park was hit in the head by a heavy steel rail.

Jamie Close of Carbondale was scrambling beneath or beside the rail when he apparently hit his head, fell and pulled the rail onto him, Eagle County Sheriff's Detective Scott Hunter said Monday.

Close had been riding his bicycle at the skatepark and was not wearing a helmet at the time of the accident.

Eagle County Coroner Jim Stryker said that the weight of the 16-foot long steel rail apparently caused a massive base skull fracture. It took three men to remove the rail from the skatepark.

Tim Clark said that his 14-year-old son told him the rail had been moved around the park but was never bolted down.

Steel beams or rails are often used in skateparks for tricks such as grinding, where the bottom of the board is run down the length of the structure.

The skatepark is housed in two abandoned buildings on the Mount Sopris Tree Farm, which is owned by Eagle County. Skaters have been allowed to build their own ramps and rails there since 1999 when the county signed an agreement with a skateboarding association which agreed to supervise it.

County officials said that the park would remain closed until they could talk to residents about whether the park has been properly supervised.