From here
"Fire crews are battling a 120-acre fire that developed Thursday afternoon in the Merced River canyon near Briceburg in Mariposa County. The fire started near the location of the temporary bridge built after the 2006 Ferguson Rock Slide.
Fire officials believe the fire was started by a motorhome.
Highway 140 is closed east of Mariposa. Visitors to Yosemite should use highways 120 or 41"