Oakland firefighters discovered about 200 marijuana plants while responding to a one-alarm blaze Monday evening, a fire battalion chief said.
The fire was reported at a two-story house near 25th Avenue and Foothill Boulevard at around 5:35 p.m., Battalion Chief Lisa Baker said.
The blaze was under control within about 20 minutes and no injuries were reported.
Firefighters discovered a marijuana operation but "at this time we don't know if it was legal or illegal," Baker said.
Baker said the owner of the house told fire officials the home was being rented out and no one was in the house when the fire started.
The cause of the blaze is under investigation but was possibly caused by an electrical overload, Baker said.