The so-called Palos Fire broke out shortly before 2:30 p.m. and burned approximately 20 acres within about an hour. The fire is 41% contained as of 4:48 p.m., fire officials said.
Firefighters declared a second alarm fire, which escalates emergency response and increases the number of resources.
The Los Angeles County Fire Department said the blaze was spreading at a moderate rate of spread.
In addition to the three structures burning in the area, the fire was threatening other structures nearby on N. Casalero Dr., according to fire officials.
The fire forced the evacuation of least six homes, with evacuees heading to nearby Los Altos High School, 15325 Robles Ave., in Hacienda Heights, according to a deputy at the sheriff's Industry station.
The Los Angeles County Emergency Operations Center has declared an evacuation warning for the following zones within La Habra Heights and Hacienda Heights:
- LAC-E613-B
- LAC-E615-B
- LAC-E618-B
- LHH-772-A
For more information, go to lacounty.gov/emergency.
The Los Angeles County Sheriff's Department encouraged residents within those zones to begin preparing for potential evacuation orders.
Palos Fire in La Habra Heights burns at least 3 structures
Firefighters said one person and a horse were being evaluated, but no further details on injuries were known.
The cause of the fire is under investigation.
This is a developing story. This article will continue to be updated as more information becomes available.
City News Service contributed to this report