The so-called "Volcano Fire" broke out Wednesday just west of Murrieta, near Clinton Keith and Tenaja roads at about 11:30 a.m.
The fire destroyed one two-story home and caused injuries to three firefighters.
Crews say the cool overnight hours were a big help in improving containment lines, and they expect to have full control by 8 p.m.
Cal Fire investigators said they believe the fire was started by motorized brush-clearing equipment.
