Officials say a fire that destroyed 43 homes last year in a largely rural area north of San Francisco was sparked by an illegal marijuana growing operation.

California Department of Forestry and Fire Protection spokeswoman Janet Upton said Wednesday the fire was started by a faulty water heater near a site where about 100 marijuana plants were being grown.

The fire burned about 108 square miles in Lake, Yolo and Colusa counties.

Upton says the case remains open and two suspects are believed to have fled the country.

The fire was the second most destructive in the Lake County area last year, behind a fire that destroyed more than 1,300 homes.

Firefighters are currently battling another major blaze in the county.