Crews were called to a single-family home in the 3900 block of La Cresenta Road around 8:10 p.m., where they found heavy fire coming from an attached garage, according to fire Battalion Chief Brian Lowry.
The home's four residents had safely evacuated the house, but two pet cats remained inside. Firefighters were able to find the animals in a back bedroom and bring them outside to safety, Lowry said.
Multiple hose lines were used to attack the blaze, which damaged the home's living area as well as the garage.
Crews were able to stop the fire from spreading to the rest of the house, but the residents were displaced due to the damage, Lowry said.
The blaze caused an estimated $65,000 in damage, including to a car in the driveway.
Investigators believe the fire was started by discarded fireplace ashes placed in the garage, the battalion chief said.
Fire officials are reminding residents to allow fireplace ashes to cool in the fireplace before disposing of them. Ashes should be placed in a tightly covered metal container that is kept at least 10 feet from a home or building, and should not be directly emptied into a trashcan.