APPLE VALLEY (CBSLA.com) — Firefighters are working to mop up the wind-driven River Bottom Fire, which has burned 185 acres and is 95 percent contained.

The fire broke out Tuesday morning at Mojave Narrows Regional Park.

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Authorities say firefighters are having a difficult time accessing a ridgeline on the east side of the riverbed due to steep terrain, dense vegetation and very unstable ground.

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About 50 firefighters and hand crews are on the scene to mop up the fire, and bulldozers from the San Bernardino County Fire Department are working to shore up containment lines around the burn area. Crews will remain in the area on Friday as a precaution, officials said.

Officials say there was a report of one injury, to an inmate hand crew member who fell into a burned out stump hole. He was taken to a hospital for treatment.

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The fire’s cause has been determined as accidental.