At least one person was killed and 73 were injured in an explosion and fire at a chemical plant in Louisiana.

State police Captain Doug Cain said a hazardous material crew going through the plant in Geismar found one person dead.

The cause of the blast was not immediately known.

Eight of the injured were taken to Baton Rouge Medical Center, where one was listed in critical condition and two others were in serious condition.

Early tests did not indicate dangerous levels of any chemicals around the plant, about 30km southeast of Baton Rouge.

Louisiana Governor Bobby Jindal said monitors had yet to detect dangerous levels of emissions from the explosion and a fire burning the petrochemical propylene.