The victims were struck just before 1 p.m. PST, when a vehicle drifted across three lanes, hit a utility pole and then rammed into a bench at the bus stop, Officer Bryan Galbreath said.
The driver of the vehicle was treated for minor injuries and then taken to a police station for question, the Riverside Press-Enterprise reported.
Police have not released the names of the victims. The two who died at the scene were identified as a woman and a female minor, and the two who were taken to Riverside Community Hospital with severe injuries were identified as a woman and a man.
Galbreath said there was no indication that speed or alcohol or drug impairment were factors in the crash.
McPhee, Cokas 'working on their marriage' after affair
Beautician charged with giving client fatal silicone butt injection