Updated

Residents of about 200 homes in Monrovia have been forced to evacuate after a brush fire erupted in the San Gabriel Mountain foothills east of Los Angeles.

City officials say the blaze was sparked by equipment used by a gardener working the backyard. Flames spread to the hillside behind the residence, scorching 170 acres.

The fire is 10 percent contained. It is not immediately threatening homes, but authorities ordered the evacuations as a precaution.

As the Monrovia fire burned, a four-acre grass fire ignited across town near Interstate 405, forcing the closure of southbound lanes for about an hour and causing traffic to back up for miles. That fire has been contained.