A fire sparked by an explosion at a petrochemical plant  near Baton Rouge, La., injured more than 30 people. Area residents were advised to stay indoors with windows and doors closed, though tests showed no signs of elevated chemical levels nearby.

A spokeswoman from the Department of Environmental Quality said three or four people were transported by helicopter to local hospitals, and ground ambulances transported about 30 people.

The fire has been contained, and the flow of chemicals to it cut off, the company said in a statement.

The plant, owned by The Williams Companies Inc., makes highly flammable gases used as basic building blocks of other substances in the petrochemical industry. According to the company’s website, the plant produces more than a billion pounds of ethylene and 90 million pounds of polymer grade propylene annually.

The Texas industrial accident lawyers at Schechter, Shaffer & Harris, L.L.P., Accident & Injury Lawyers  represent workers injured in chemical plant explosions across the United States.