Four of the children were in critical condition when firefighters arrived but they were stabilized and were in serious condition at a hospital, city fire Capt. Jaime Moore said. Everyone was expected to survive, he said.
Some of the victims were trapped under the powder blue Cadillac before witnesses helped pull them out, Moore said. Helicopter footage from NBC4 showed a child in a pink T-shirt being loaded into an ambulance and a Hello Kitty backpack lying in the street nearby.
Police identified the driver as Preston Carter and said he was being very cooperative.
Carter talked to television reporters just after the crash, saying he has a license and will be 101 years old Sept. 5.
"My brakes failed, it was out of control," Carter told KCAL-TV.
Asked about hitting the children, Preston said: "You know I'm sorry about that. I wouldn't do that for nothing on earth. My sympathies for them."
After an initial investigation, it appears Carter was pulling out of a parking space, but instead of backing into the street, he backed onto the sidewalk, police Capt. George Rodriguez said. The car hit a group of people who were gathered to buy snacks from a street vendor, Rodriguez said.
"I think it was a miscalculation on his part, the gentleman is elderly," said Rodriguez, who added there is no age limit for having a driver's license in California. "Obviously he is going to have some impairment on his decision making."
Older drivers have been involved in other tragedies. In 2003, an 86-year-old man mistakenly stepped on the gas pedal of his car instead of the brake and then panicked, plowing into an open-air market in Santa Monica. Ten people were killed and 63 injured.
According to California's Department of Motor Vehicles, people over age 70 must renew their driver's license in person, rather than via the Internet or by mail. Older drivers can also be required to take a supplemental driving test if they fail a vision exam, or if a police officer, a physician, or a family member raises questions about their ability.
Rodriguez said the collision was being investigated as an accident, and Carter was not under arrest. He has a valid driver's license, Rodriguez said.
Carter's Cadillac still sat draped in police tape on the sidewalk across from Main Street Elementary more than two hours after crash. The school is about five miles southwest of downtown Los Angeles.
About 130 students remained on campus in afterschool programs, and their parents were being called to pick them up early, said Rowena LaGrosa, an operations manager for the Los Angeles Unified School District.
The Associated Press, KABC-TV Los Angeles, CA, contributed to this report.