Firefighters were able to contain a small brush fire that sparked along the 118 Freeway near Chatsworth on Tuesday.
The flames broke out around 6:30 p.m. near 10800 North Santa Susana Pass Road, just outside the northwest corner of Chatsworth city limits, the Los Angeles Fire Department said in an alert. It was being dubbed the Rocky Peak Fire.
It spread to about 3 acres within an hour, the agency said.
Aerial video showed a rocky hillside smoking heavily beneath a housing development, but officials said no structures were immediately threatened.
Measures had been taken to protect the homes, the Fire Department said.
The flames were burning uphill in medium brush and being driven by topography, firefighters said.
Nearly 100 LAFD firefighters were at the scene, and personnel from the Los Angeles County and Ventura County fire departments also responded to assist.
No injuries were reported.