Traffic lights in the immediate area also went out.
Police set up stop signs and redirected traffic, while firefighters went to the courthouse and rescued two women from elevators that were stuck between floors.
Hundreds of people gathered outside the courthouse, including juror Shannon Davis, who said she sympathized with the stranded women.
"I felt really bad for them because the elevators are really old, and really slow, and awful as they are, so to be trapped in them would really be a nightmare," Davis said.
All trials were canceled for the day, and people in the jury pool were excused. However, anyone with essential court business was told to return at 1:30 p.m., when the court was scheduled to reopen.
By 10 a.m., Southern California Edison crews had restored power to most of the affected customers.