Firefighters battled heavy flames and explosions at a Los Angeles Department of Water and Power plant in Southern California on Saturday night, according to the Los Angeles Fire Department.
The electrical incident initially left 140,000 Valley customers without electricity, authorities said. By 10:15 p.m., power had been restored to nearly 50,000 customers, reducing the number of impacted customers to 94,000.
By around 8:50 a.m. Sunday, power had been fully restored, the LADWP said. People in the north end of San Fernando Valley who were still experiencing outages were asked to check their circuit breakers.
The fire was reported at 6:43 p.m. in the 18900 block of Parthenia Street in Northridge.
Heavy fire and an explosion were noted in high voltage electrical equipment at the J power receiving station.
The J power receiving station serves the northeast part of the San Fernando Valley, according to the LADWP.
The fire was in an energized storage vault with 50-60,000 gallons of mineral oil, fire officials said.
Eighty-four firefighters let the flames burn while DWP workers de-energized the facility, then they put water and foam on the fire. They did not want to cause more damage by putting water on the flames while the plant was energized. No injuries were reported.
Firefighters had the bulk of flames out in two hours but were expected to remain on the scene into the morning to watch for flare-ups, he said.
"High voltage electricity comes into stations like these and is then distributed at lower voltages to customers in the surrounding area," the LADWP said in a statement.
All power was cut off to the station for safety and approximately 140,000 customers in the San Fernando Valley were initially affected and without power. Affected areas included Northridge, Winnetka, Reseda, Lake Balboa, Tarzana, North Hills, Granada Hills, Chatsworth, West Hills, Canoga Park, and Woodland Hills.
Utility officials said the cause of the fire was accidental and attributed it to a "mechanical malfunction," according to Los Angeles Fire Department Public Service Officer Brian Humphrey.
Videos posted to social media showed large plumes of smoke billowing into the air.
Aerial footage from NewsChopper 4 showed a large fire response on scene battling the blaze at the LADWP facility.
The electrical incident forced a closure of Parthenia Street in both directions between Vanalden Avenue and Yolanda Avenue in Northridge, according to the Los Angeles Fire Department.
Drivers were advised of delays and congestion in the area and told to use alternate routes.
The power outage comes as much of California baked in heat that broke records. A record that stood 131 years in Los Angeles was snapped when the temperature spiked at 98 degrees downtown.
City News Service and the Associated Press contributed to this report.