LOS ANGELES — A 12-acre brush fire in Irvine, Calif., over the weekend was caused by a golfer who accidentally chipped a rock at Shady Canyon Golf Club, officials said.

More than 150 firefighters, including helicopters and hand crews, from around Orange County battled the blaze, said Orange County Fire Authority Capt. Greg McKeown.

The fire spread across two hillsides in dry-as-tinderbox conditions.

“”Usually, we’re able to close out the fire season in the winters here,”” McKeown added, “”but we haven’t been able to do that since 2006. That’s just how dry it is out there.””

McKeown said no charges have been filed against the golfer, whose name has been withheld. Apparently, he was trying to hit his ball out of the rough when he struck the rock, which sparked the blaze at 12:07 p.m. Saturday, officials said.

“”There’s a lot of dead growth out there,”” said McKeown, adding that there are thousands of acres in Orange County ripe for wildfires.