The Getty fire—a Southern California wildfire that has destroyed 12 homes so far—was sparked after a tree branch fell on power lines on Monday, the Los Angeles Times reports. Los Angeles Mayor Eric Garcetti told reporters that video footage showed a branch breaking off a eucalyptus tree on North Sepulveda Boulevard, then hitting power lines and sparking the more than 600-acre blaze. The power lines were reportedly operated by the Los Angeles Department of Water and Power, which at that point had not shut off service to any of its customers—unlike PG&E in Northern California.

Andrew Kendall, senior assistant manager of the DWP’s power system, previously said the utility wouldn’t need to shut down power because it serves significantly fewer customers than other companies and covers an area that is “no more than a five- to seven-minute” distance from Los Angeles Fire Department response. “So right now, at this time and based on previous history, we don’t feel we’re at a point where it’s prudent to do a shutdown,” he said. It was only after the fire started that the utility took three of its circuits out of service, leaving 2,600 customers without power. News of the Getty fire’s origin comes as PG&E power lines are also being considered as the cause for fires in the northern part of the state.