State police Trooper Russell Graham says officials had reports that vinyl chloride was released in the Thursday morning blaze, but it was unclear how much of the flammable and highly toxic chemical may have escaped.
Ami Johnson, a spokeswoman for the Ascension Parish emergency office, says the few people who live in the immediate area were told to close windows and doors and turn off air conditioning units.
The plant in Geismar, south of Baton Rouge, is owned by Houston-based Westlake Chemical Corp. It is one of several chemical plants and oil refineries that line the river.
A spokesman for the company could not immediately provide details of what caused the fire.
