John Wayne Airport near Los Angeles shut down as power went out to the entire area Friday night.
The airport, which is in Santa Ana, California, about 45 minutes southeast of downtown Los Angeles, was impacted by a fire at a substation in nearby Irvine. The power outage caused a full ground stop at the airport, including no departures or arrivals.
"There is currently a full ground stop. Any inbound flight to JWA will be diverted," the airport tweeted. "Guests who are picking up passengers are advised to call the airline for more information."
There were 28,000 customers without power in Irvine and Newport Beach after the fire, which started at about 6:30 p.m. local time.
John Wayne Airport is the second-largest airport in the area behind Los Angeles International Airport. It has about 9 million passengers per year.
The airport tweeted at about 9 p.m. that power was "slowly coming back online" at the terminal.
Flights are still not operating despite power coming back online. A full ground stop will be in effect until Saturday morning.
The airport was still open to private flights.
Irvine authorities said they were unaware of what caused the fire at the substation.
ABC News' Rayquan Taylor contributed to this report.