The blaze in a training area in the southwestern reaches of the San Diego County military installation was reported in the early afternoon Monday, according to the nonprofit wildfire-information service Watch Duty.
As of Monday afternoon, the burn area had grown to about 920 acres, the organization reported.
The flames were threatening structures on the base, prompting evacuations of some of its populated areas, according to Camp Pendleton public affairs.
The evacuation order for the 33 area has been lifted, and the evacuation order for the 32 area remained in effect.
City News Service, Inc. contributed to this report.