UPDATE 5:45 p.m.: The Old Fire continues to burn at 150 acres but is now 70 percent contained, according to the U.S. Forest Service in Stanislaus County.
No structures have been burned in the wild fire but four are threatened.
One firefighter was injured. The cause of the fire is still under investigation.
ORIGINAL: Firefighters are still knocking down spot fires that keep arising from a fairly small fire in the Stanislaus National Forest.
The fire started Tuesday east of Groveland in Mariposa County and has reached 150 acres in size.
Firefighters continue to find spot fires a half mile away from where the fire started.
The area is full of dead pine trees that were killed by an invasion of bark beetles.
Four buildings are threatened. One firefighter was injured.
Fifteen engines and six air tankers continue with efforts to put the fire out. It is 50 percent contained.