A fireball could be seen ballooning near the Old World Village restaurant in Huntington Beach around 8 p.m.
Witnesses reported hearing at least three explosions, according to The Los Angeles Times.
The restaurant was evacuated.
The Huntington Beach Fire Department said all of the injuries were minor.
Officials said an underground electrical vault exploded, but they were still investigating the cause.
Hundreds of customers were left without power after the explosion, The Times reported.
Huntington Beach is about 37 miles south of Los Angeles.