Ada County Dispatch says there were two chain reaction crashes involving 11-12 vehicles near milepost 5.
The sheriff's office says that only minor injuries have been reported.
The sheriff's office asked people who were up at the mountain to stay at the lodge at Bogus Basin until they could clear up the mess.
Most of the vehicles were able to drive the rest of the way down the road to the base of the foothills so deputies could interview them.
Dispatch says there was also another crash involving a car that slid off the road near the Ada-Boise County line. That crash also had only minor injuries.
Any new information will be reported as it becomes available.