"We are talking about very rugged terrain up in the mountains," Santa Clara County Sheriff's spokesman Rick Sung.
About 12 deputies started the marijuana enforcement operation at sunrise in the rugged hills near the border of Alameda and Santa Clara counties.
At 10:25 a.m., Santa Clara sheriff's dispatchers received a call from a member of the operation that a suspected grower had been shot and killed.
Authorities step up marijuana enforcement operations beginning in the summer when growers start cultivating their illegal crops. Sung says the deputies always go in fully armed.
"They have to assume that the growers at the gardens are heavily armed, and so that why they are very caution when they enter a scene," he said.
This is the second time in two years that a suspected grower has been shot and killed by a member of the Santa Clara County Sheriff's marijuana eradication team.
That shooting in 2008 happened in the Saratoga Hills.
"In that particular incident, the suspect actually aimed a shotgun at our deputies at which point, he returned fire killing the suspect," Sung said.
Investigators began reviewing details of the shooting this afternoon at the staging area. Sung says they will be here through the evening hours.
"It's going to take a little while for our personnel to hike in there, number one, not to mention all the equipment so that they can collect the evidence and claim the body," he said.
Officials have yet to release the identity of the victim, and the sheriff's office has not confirmed whether or not there were other arrests or suspects.
It is also unknown whether the illegal grow was on private or public land.