A photo taken by Andro Mammo shows the Porter Ranch neighborhood in Los Angeles engulfed in flames.
Some residents have been allowed back in or near their homes, but city officials said the danger is not over yet.
"It's not the fire itself but the danger of wind that can bring an ember blowing it someplace and seeing entire neighborhood overnight getting lit up," Garcetti said.
The Saddleridge fire is just one of the several blazes in Southern California fueled by one of those fires has left at least one person dead, and many parts of the region are under red-flag warnings — meaning there's a high risk of fire — into Saturday afternoon.
The Saddleridge Fire jumped two freeways
The Saddleridge Fire started around 9 p.m. ET and jumped the 210 and 5 freeways, and some parts those roads and the 405 were closed as orange embers lit up the night sky. By late Thursday it had gutted 60 acres; just hours later, it had grown to more than 4,000 acres, fire officials said.
The fire's cause was not immediately known.
Hector Landeros, who lives in northern Los Angeles' Sylmar neighborhood, said he heard fire trucks and police cruisers speeding through the streets as the massive flames got closer.
"In some areas, the streets have started to empty but at the front lines people are watching, waiting on the sidewalk not really knowing what to do," he told CNN early Friday. "There are a lot of people trying to get into their neighborhoods."