Police are evacuating thousands of people from homes and businesses within a 1-mile radius of the accident.
Corporal Paul Mouton says a total of six cars derailed, and two of them began to leak. He says local firefighters and state police are on the scene.
Authorities are going door-to-door in the area asking residents to leave.
Mouton says the area is mostly businesses, but there are also a few apartment complexes and a nursing home. He estimates thousands will have to be evacuated.
A local ambulance service says it's transferring 20 of the nursing home residents to a nearby hospital, two with what are described as "very minor injuries."