Thousands evacuated after freight train carrying 'highly flammable and toxic gas' bursts into flames in US

Train reportedly came off the tracks in Tennessee earlier on Thursday

The train was carrying carrying liquefied petroleum gas and acrylonitrile (Getty )

Thousands of Tennessee residents have been evacuated after a US freight train carrying highly flammable and toxic gas caught fire.

Approximately 5,000 people were evacuated following the declaration of a one-mile evacuation zone around the route taken by the CSX train near the town of Maryville, south of Knoxville.

The train, travelling from Cincinnati to Waycross in Georgia, is believed to be carrying liquefied petroleum gas and acrylonitrile - used to make plastic – and which authorities described as a "highly flammable and toxic gas." The fire was reported at around 12am last night.

The US Environmental Protection Agency warns that exposure to acrylonitrile can cause “headaches, dizziness, and nausea.” It also notes that prolonged exposure can lead to “severe burns to the skin”.

It includes two machine carriages, 45 loaded rail cars and 12 empty rail seats, CSX spokesperson Kristin Seay told ABC News.

Although initial media reports claimed the train had derailed, Blount County Sheriff’s spokeswoman Marian O’Briant said that only one carriage caught fire and there was no derailment. Mrs O'Briant said Hazmat crews have attended the scene as local firecrews evacuated the nearby area.

“Evacuation time could last anywhere from 24 to 48 hours, but we'll get word out as soon as we can,” she added.

There are no reported injuries however seven firefighters had been taken to hospital after breathing in the noxious fumes, NBC News reported.

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