ATMORE, Ala. — A plant that produces agricultural chemicals caught fire Saturday in southwest Alabama, blanketing the area with potentially hazardous smoke and prompting an order for people to stay inside.

Police said the fire began before dawn at a factory operated by Tiger-Sul Products, and crews were still on the scene hours later. No injuries were reported.

Atmore Police Chief Chuck Brooks told WALA-TV that sulfur was burning in a warehouse, and 200 to 300 residents nearest the plant were asked to stay inside their homes as a precaution.

“It is extremely hard to breathe near the warehouse,” Brooks said.

The Tiger-Sul website said it produces products including agricultural sulfur, which can cause skin irritation and breathing problems if inhaled. Company officials did not return an email message seeking comment.

Sheriff’s officials closed part of U.S. 31 because of the smoke and diverted traffic to Interstate 65.

The plant is located about 50 miles (80 km) northeast of Mobile in a town of about 10,000 people.