California ? Firefighters waged an aggressive ground and air assault Sunday against a wind-fanned wildfire that erupted in the San Gabriel Mountains and threatened a popular resort community.

Crews spent the day cutting fire lines while battling erratic winds. Helicopters and air tankers, which were briefly grounded due to the gusty weather, dropped water and retardant on the blaze, which grew to 7,500 acres.

Flames, chewing through chaparral and timber, advanced within a quarter-mile of the mountain resort community of Wrightwood, which was under mandatory evacuation. By Sunday afternoon, firefighters were cautiously optimistic about keeping the fire at bay, aided somewhat by cooling temperatures and higher humidity.

Officials stressed the fight was far from over. Firefighters had to contend with shifting winds, which gusted up to 50 mph and occasionally dropped to zero.