Santa Barbara County Sheriff Bill Brown, speaking at a news conference today, said investigators believe the La Brea fire was started by Mexican drug traffickers because of the size of the marijuana garden and the equipment found at the campsite where the fire began.

Brown stood in front of large poster showing the blackened campsite. He said that 30,000 plants, ranging from 2 feet to 6 feet, were discovered at the remote pot farm. Also found were stacks of propane tanks, melted irrigation tubing, empty canisters of fertilizer, mounds of trash, a torched cooking stove and a semiautomatic rifle.

The growers diverted a nearby stream and planted the garden on the side of a mountain.

The suspects apparently fled as firefighters approached the source of the fire and are still at large, Brown said. He warned rural residents not to approach anyone leaving the forest.

[Updated, 2:20 p.m.: It's been a record year of pot seizures for the U.S. Forest Service and sheriff's department narcotics agents in Santa Barbara County. So far they have pulled 225,058 plants, with a street value of about $675 million. In late July, agents eradicated 113,000 plants in a camp not far from the one where the fire started.]

Brown said it's virtually impossible to get rid of all the marijuana grown in forests.

"The reality is that we could have an army out there and not be able to cover all of that ground," he said.

Every year, smaller fires are doused that have been started by suspected drug traffickers in the forest, said Russ Arthur, a special agent with the U.S. Forest Service. But the 90,000-acre La Brea fire east of Santa Maria is the largest ever, he said.

-- Catherine Saillant in Santa Barbara

Photo: Campsite, including a blackened camp stove in the background, where the fire is believed to have started. Credit: U.S. Forest Service and Santa Barbara County Sheriff's Department