Idaho State Police say a crash that occurred Tuesday afternoon blocked State Highway 50 near Hansen for about two hours.  37 year old Joshua Stallings of Weiser was driving a semi-truck loaded with roofing materials when he swerved to avoid a vehicle that pulled in front of his truck from 3900 North Road.  Stallings lost control and the truck rolled blocking both lanes of the highway.  The driver of the vehicle that reportedly caused the accident did not stop and police would like your help in locating them.  There is no description of the vehicle.  But police are asking anyone with any information to call them at 324-6000.