A 100-year-old man has backed his car on to a pavement and hit 11 people, including 9 children.
The collision happened across from an elementary school in south Los Angeles on Wednesday.
Four of the children were in a critical condition when firefighters arrived, but were stabilised and are in serious condition at a hospital, according to the city's fire chief.
Everyone is expected to survive, he said.
Police identified the driver as Preston Carter and said he was being very co-operative.
Asked about hitting the children, Mr Carter said: "I'm sorry, I have sympathy for them. I wouldn't have done it for nothing on earth."
According to California's Department of Motor Vehicles, people over the age of 70 must renew their driver's licence in person, rather than via the Internet or by post.
Older drivers can also be required to take a supplemental driving test if they fail a vision test, or if a police officer, physician, or family member raises questions about their ability.
Police says the collision is being investigated as an accident, and Mr Carter has not been arrested.