Marine engineers from Camp Pendleton were detonating explosives in the Cleveland National Forest around the time of the Jim fire's ignition Wednesday morning, authorities have confirmed.
The fire, which has been burning for two days inside the forest near the Riverside-Orange County line, was 50% contained and holding at 553 acres Friday morning.
The official cause of the fire remains under investigation. Cleveland National Forest Service spokesman Nathan Judy acknowledged that crews were in the forest around the time of ignition.
