A vegetation fire spread over three rugged acres of grassy oak woodland above Deer Park School in Fairfax just before 5 p.m. on Saturday. The fire was contained within three hours, with the help of three departments, 89 firefighters, four water-dropping aircraft and a spotter plane. “We don’t know exactly how it started,” said Marin County Fire Department Battalion Chief Mike Giannini. “The fire marshal did find fireworks near the origin, so it’s suspected that fireworks were the cause.” The Marin County, Ross Valley, and Cal Fire departments coordinated the suppression, which required two water tenders and 3,000 feet of hose. No suspects have been identified and no injuries or structural damage was reported. “If this happened in an area where the smoke wasn’t as readily visible, this could have been the catastrophic fire that everyone fears on Mt. Tam,” Giannini said. “We were fortunate it was identified early, and we had a lot resources we could put on the fire.”