A brush fire that broke out Monday afternoon in the hills around La Habra Heights has destroyed one structure and is threatening others, triggering an evacuation warning in the area.

The Palos fire began just after 2:30 p.m. in the 2400 block of Las Palomas Drive in Whittier, according to the Los Angeles County Fire Department. The fire had burned 20 acres as of 4:15 p.m., said Los Angeles County Fire Department spokesperson Keith Navarre.

Authorities issued an evacuation warning for surrounding neighborhoods including many streets in La Habra Heights as crews worked to contain the blaze.

Footage of the fire broadcast on KTTV Monday afternoon showed at least one structure — which authorities said was a home — engulfed in flames.

Navarre says the Fire Department has allocated 76 units and 250 personnel to the fire. The firefight includes helitankers, he said.

The fire broke out in a canyon and has been moving up the canyon walls, he said. Some firefighters have hiked down into the canyon to contain the flames, while others are focused on defending the homes along an adjacent ridgeline, Navarre said.

La Habra Heights’ narrow roads, he said, have made firefighting access difficult.

The area covered by the evacuation warning can be found here.

It is roughly bounded by Puenta del Este Drive and Hacienda Road on the east; Casalero Drive, Lupin Hill Road and Las Palomas Drive on the west; Windrush and Gun Tree drives to the north; and Encanada Drive to the south.

It includes a portion of the Puente Hills Preserve as well as the Hsi Lai Temple to the east and some businesses at Colima Road and South Hacienda Boulevard.