Sonoma County sheriff's narcotics detectives were investigating a Saturday morning fire in an hillside home in Fetters Hot Springs where hundreds of marijuana plants were being grown.
Much of the cannabis was destroyed during the fire, which was reported at 7:16 a.m. by a neighbor who described it as an orange glow on the back side of the home at 17270 Keaton Ave.
There was no one home at the time, and investigators were attempting Saturday to identify the occupants.
The three-story home is on a hill and surrounded by oak trees, with the structure's third floor at street level. A Sonoma Valley Fire and Rescue crew was the first to arrive at the scene about six minutes after the call, Division Chief Bob Norrbom said.
He said that when crews arrived, the first and second floors in the back of the building were burning. Crews immediately worked to keep the fire from spreading to nearby residences.
Fire officials said it was difficult to gain access to the house because those responsible for the marijuana operation boarded up the windows and doors with wood and drywall.
"Our normal routes of entry were all blocked, so we had to cut a hole through the metal garage door," Norrbom said.
There were hundreds of marijuana plants inside the house, and nearly every room on the first and second floor "had some kind of marijuana grow going on," he said. The fire was extinguished after about 40 minutes.
Sheriff's narcotics detectives spent much of the day investigating the site and collecting evidence. Officials said the PG&E meter had been tampered with and the house was illegally drawing electricity.
The back of the home was badly burned, and the much of the vinyl siding on the side of the house was melted and peeling away.
Inside one of the lower-floor rooms, dozens of budding marijuana plants could be seen through a broken sliding-glass window. Pieces of drywall that once covered the window lay on the ground.