Firefighters were battling a wildfire in steep and rocky terrain in the Angeles National Forest above Arcadia as a heat wave gripped the region.

The Chantry Fire, which broke out Sunday near Santa Anita Canyon, had burned at least 5 acres with 50 percent containment by 11 a.m. Monday, the U.S. Forest Service said. 

An evacuation warning was issued for recreational cabins and other buildings in the area.

More than 200 firefighters and heavy machinery, including two air tankers and five helicopters, were dispatched to the scene. Fire crews from Los Angeles County, Sierra Madre and Arcadia were also assisting.

The first heat wave of the year brought triple-digit temperatures and excessive heat warnings to parts of Southern California.