SAN DIEGO — Crews are starting to get a handle on a wildfire that has burned hundreds of acres in the Southern California wilderness since it broke out Wednesday afternoon.

The Jim Fire, which is burning in the Cleveland National Forest near the Riverside-Orange County line, is now 15% contained, the U.S. Forest Service said Thursday morning. It’s held relatively steady since growing to 500 acres by 7 p.m. the previous evening, only increasing to 553 acres.

Officials say they’re entering a new stage in the firefight.

“Overnight little fire activity was observed by the crew of firefighters that patrolled and monitored the fire perimeter while constructing containment lines,” a forest service update reads. “Today ground crews will continue to build hand and dozer lines around the fire and utilize water-dropping helicopters to assist with any remaining hotspots.”

Smoke from the blaze was visible from parts of San Diego County Wednesday, prompting an alert from local authorities. The region is not threatened by the flames, according to North County Fire Protection District.

The fire is burning through chaparral and brush in a relatively remote area known as Holy Jim Canyon. No buildings are threatened and no injuries have been reported, according to the forest service.

The blaze broke out in a drainage bottom around 11:30 a.m. Wednesday and spread uphill, ballooning to hundreds of acres by early afternoon, officials said. U.S. Forest Service Law Enforcement is now investigating the cause.

Orange County Fire Authority and Cal Fire resources have aided the forest service firefighters leading the effort. Air tankers remain “on standby” in the case of flare-ups Thursday.