Officers responded to the school at 55 Christen Ave. at about 2:40 p.m. on reports of a major-injury crash. They learned that the driver was attempting to park his car in the school parking lot when he lost control of the vehicle.
The car went over a curb and into an area on campus where many students were walking, and struck three children, police said.
One of the victims was dragged across the blacktop, police said. The three children were taken to San Francisco General Hospital. All are expected to survive.
"They're non-life-threatening, but they're pretty significant," Sgt. David Mackriss said of the injuries.
The driver of the vehicle was uninjured and the crash remains under investigation.