The fire is burning above Glendora in the Angeles National Forest. Firefighters said the Camp Williams Mobile Home Park is no longer in danger.
The blaze was 48 percent contained as of Thursday morning. More than 4,100 acres have burned since the wildfire started on Sunday afternoon.
The fire was expected to be fully contained Sept. 13. Crews are also assessing the damage and the potential for mudslides when the rainy season hits later this year.
The cause of the fire remains under investigation.