A fire late Saturday at a Los Angeles Department of Water and Power facility forced officials to cut off power to about 140,000 city residents, leaving them without air-conditioning for roughly 12 hours during a record-breaking heat wave.

The fire, which broke out at a receiving station in the northern Los Angeles neighborhood of Northridge, burned intensely on and around high-voltage equipment, said Brian Humphrey, a spokesman for the Los Angeles Fire Department.

Columns of smoke billowed over the San Fernando Valley as firefighters worked for about two hours to extinguish the blaze, he said.