An explosion at the Chevron refinery in Richmond, Calif., on Thursday at 2:30 p.m. resulted in a fire that spewed black smoke over the surrounding area.
An estimated 600 nearby residents were taken to area hospitals with symptoms of nausea and a metallic taste in their mouths or a burning sensation in their throats.
According to Chevron, the explosion occurred in a hydrocracking unit, a processing unit that converts gas oil into gasoline and jet fuel. The 30 employees who work in the unit have been accounted for without injury.
Chevron's fire department personnel first responded to the fire and called in assistance from the Richmond Fire Department and six other response organizations.
Reports said that the black smoke was visible across the bay in San Francisco and Marin County. It took firefighters approximately 5-1/2 hours to contain the blaze. After the explosion, Chevron activated its emergency response procedures and notified area agencies.
The hydrocracking unit in the refinery has been shut down. All other unaffected areas of the refinery, which employs more than 1,450 employees, are still in operation.
Chevron industrial hygienists have sampled the air and toured the perimeter of the facility and surrounding community. They said initial indications are that there were no harmful substances in the air.
Health officials, however, suggested that neighbors remain inside with their doors and windows closed. The cause of the explosion is being investigated.