SUNOL, Calif. -- Alameda County sheriff's deputies seized more than 22,000 marijuana plants with a street value in excess of $6 million this week at the biggest outdoor growing operation the sheriff's office has ever encountered, authorities said.

About two weeks ago, a motorist east of Sunol on Calaveras Road reported seeing a teenager wearing camouflage clothes run up a creek bed from the road, Sgt. Shawn Peterson said.

The sheriff's office launched an investigation, and on Thursday a marijuana eradication team found 24 inter-linked pot gardens, three campsites and three make-shift kitchens in the Calaveras Road area, on land that is owned by the San Francisco Water District and feeds the Calaveras Reservoir, Peterson said.

The team found 22,838 seedlings about 20 inches tall that were fed with a fresh water supply directly from two creeks on a ridge.

Two men in their late 20s were seen working in the garden and wearing woodland camouflage, and deputies attempted to take them into custody.

The two suspects ran, one dropping a loaded semi-automatic handgun during the chase, Peterson said. The suspects managed to evade capture by escaping through heavy brush and steep ravines, Peterson said.

The eradication team remained at the site all day Thursday and Friday, he said, and found tents, sleeping bags, numerous pesticides and bags of fertilizer.

Anyone with information regarding the pot farms or any other grow operations is asked to call Sgt. Shawn Peterson with the Alameda County Sheriff's Office at (510) 667-3633.

Peterson said last year deputies found about 7,000 plants during probably the second-biggest eradication they had encountered.

He said that in August, the 22,000 plants found Thursday might have been anywhere from 6 to 8 feet tall.

The U.S. Drug Enforcement Administration estimates the average street value of a mature pot plant to be around $3,000, according to the DEA Web site.