Up to 400 people were evacuated from their homes Saturday after corrosive chemicals leaked from a tanker truck in Southern California (search), sending a plume of toxic gas into the sky.

Firefighters went door to door in the unincorporated area north of Riverside (search), ordering neighbors out of their homes, after more than 200 gallons of the unidentified chemical spilled onto the ground while the truck was parked in a driveway. No injuries were reported.

The gas plume was believed to be hazardous, so cleanup crews wore protective suits while police remained upwind from the spill.

Officials believe the substance was some type of acid or mix of corrosive chemicals, Riverside County Fire Capt. Rick Vogt said.

Residents expected to return by late Saturday.