The highway patrol says 11 high school students were on the Madera Unified bus when a car in front of them slowed down to make a right turn into an alleyway.
Investigators say the bus didn't stop in time and ran into the side of the car. The school district is now investigating the driver's role in the accident.
Four of the students were taken to Madera Community Hospital with minor injuries. Both people in the car were also treated for minor injuries, but officers later arrested the driver.
"After further investigation the driver of the small sedan was found to be under the influence," Officer Mark Cosentino said. "He was taken into custody and booked in the Madera County jail."
That driver has been identified as 37-year-old Andy Williams. He is now out of jail on bail.