Three ethanol holding tanks caught fire at a NuStar Energy petrochemical storage facility in Contra Costa County, California, according to local fire services.
Authorities have advised residents of nearby areas not to go outside and to close all their doors and windows tightly.
A county-wide state of emergency has been declared; firefighters could not cope with the fire immediately, they used all the forces and means available to local rescue services in the region to fight the fire.
The cause of the fire remains unclear.