Firefighters quickly extinguished a small grass fire Saturday afternoon off southbound Highway 101 near the River Road exit south of Windsor, temporarily closing several freeway lanes for less than an hour.

The half-acre blaze started when an overheated car pulled over on the side of the freeway and ignited some grass, said Battalion Chief Dave Cornelsen of the Windsor and Rincon Valley Fire Districts. No structures were damaged.

The fire was reported at 12:49 p.m. and about 15 firefighters from Windsor, Rincon Valley and Santa Rosa put it out within half an hour, Cornelsen said. While firefighters were working, the California Highway Patrol closed a segment of the freeway to one lane for about 45 minutes, according to Cornelsen.