BOISE -- Ada County Sheriff's deputies are investigating a fatal motorcycle crash.
A spokeswoman for the sheriff's office says it happened Friday night around 8:15 on Highway 21 near the Diversion Dam by Lucky Peak.
Ada County Deputies say a 51-year-old Boise man riding his motorcycle south on the highway, when he hit a basketball-sized boulder on the shoulder of the road, lost control and crashed.
Officials say the man was not wearing a helmet and suffered from extensive head injuries and died instantly.
The highway was reduced to one lane while detectives investigated the crash.