More than 5,000 people were evacuated after part of the train caught fire.
Local media are reporting that the CSX transportation train derailed south of Knoxville in Blount County in Tennessee.
On its Facebook page, the Blount County Sheriff’s Office said that the evacuations could last for up to 48 hours. A shelter for people affected has been set up at a high school.
A spokeswoman from the Blount County Sheriff Department said seven police officers were taken to hospital after breathing in fumes from the fire.
The train was carrying Acrylonitrile which authorities have described as a “highly flammable and toxic gas.” The US Environmental Protection Agency says “exposure of workers to acrylonitrile has been observed to cause mucous membrane irritation, headaches, dizziness, and nausea.”
This is not the first time this year that a train carrying chemicals has derailed. In May six cars, three of them carrying hazardous chemicals, derailed prompting a state of emergency to be declared in Addis, Louisiana. In February a CSX train carrying oil in West Virginia derailed and burned for more than a day.
Last month a train travelling from Washington D.C. to New York City derailed killing eight people and injuring more than 200.