The fire destroyed an untold number of marijuana plantations in the Angeles National Forest, a growing hub for pot-growing operations in California.

LOS ANGELES — The wildfire that has ravaged a national forest near Los Angeles has burned one plant species that authorities were happy to see go: marijuana, lots of it.

The fire destroyed an untold number of marijuana plantations in the Angeles National Forest, a growing hub for pot-growing operations in California.

Three marijuana cultivation areas identified just before the fire are believed to have burned, Los Angeles County Sheriff's Lt. Phil Abner said, and many more are assumed to have been destroyed.

Sheriff's officials don't know how many plants were in the three burned grow areas. Because marijuana is grown in a hodgepodge style and the plants are concealed by tall brush, it is hard to gauge from helicopters the size of each grove. Groves can host anything from several hundred to several thousand plants.

"I don't doubt that some burned that we hadn't identified," said Abner, who heads up a multi-agency force tasked each growing season with eradicating marijuana.

In the days the fire was burning most ferociously, several apparent pot plantation laborers were spotted spilling from the forest and walking down highways away from the flames, Abner said.

"With no clear explanation as to why they were," he said. "The educated speculation is they came out of the marijuana groves."

And it appears they are already starting to return to the forest.

On Saturday, a team of hotshot firefighters working near a popular and badly burned recreational area high in the rugged San Gabriel Mountains found singed water lines with new ones already lying alongside them. Fearing for their safety, the firefighters called the sheriff's department, whose deputies arrested a Mexican national found hiding out with a .22-caliber rifle, Abner said.

Before the fire, authorities this year had already yanked about 595,000 plants from the national forest and surrounding areas, an amount far exceeding previous years. With each plant thought to produce about $4,000 worth of marijuana, Abner estimated the street value of the haul to be about $2.4 billion.

Across California, more than 4 million plants have been pulled by authorities this year, almost entirely from public lands, said Michelle Gregory, a spokeswoman with the state Bureau of Narcotics Enforcement.

Aside from the obvious dangers associated with having armed drug growers roaming the countryside, authorities are also concerned about marijuana plantations' environmental impact.

Barrels of pesticides and herbicides can spill into the groundwater system, especially after a wildfire, and growers leave trash, gasoline and other camping equipment lying around while they spend weeks tending their crop, said Lt. Joe Nunez of the sheriff's narcotics bureau.

They've also been blamed for starting fires.

Marijuana growers with possible ties to Mexican drug cartels caused an 88,650-acre wildfire in Santa Barbara County last month, investigators said. That blaze was sparked by a cooking device left by suspected drug traffickers at an encampment.

The current fire is not thought to have been started by marijuana cultivation, and investigators are looking for an arsonist thought to have set the blaze next to a mountain highway. Because two firefighters were killed when their truck crashed down a ravine as they fled flames, the probe is a homicide investigation.

The fire has charred 250 square miles of national forest and more than 80 homes, but could be fully contained any day.

Abner said the marijuana-growing areas are manned almost invariably by Mexican immigrants, some of whom have been tricked into tending the plants. He said some claimed to have been standing outside a Home Depot in Los Angeles, looking for day labor, when a van pulled up and asked them if they knew anything about gardening.

"The next thing they know they are up there for five weeks," Abner said, afraid or unable to come down from the hillside and return to the city. "They often can't tell you who hired them. ... They just tell you they have been paid to put water on the weeds."