The latest incident involving a derailed train car carrying toxic chemicals happened early Thursday, after the train burst into flames and released toxic fumes that forced the evacuation of 5,000 people in a rural Tennessee town authorities confirmed.
Blount County sheriff's office spokeswoman Marian O'Briant confirmed the incident and said that seven deputies were treated at a local hospital for exposure to the deadly fumes.
In total 12 emergency responders were decontaminated at Blount Memorial Hospital, according to hospital spokesman Josh West who called the procedure "standard" after exposure to toxic chemicals.
The single car was part of a 60-car train carrying acrylonitrile, a chemical used to manufacture plastics, said train operator CSX through spokeswoman Kristin Seay.
The train was traveling from Cincinnati to Waycross, Georgia, when a lone car suddenly veered off the rails in Blount County, just south of Knoxville.
Officials continue to investigate the cause of the crash and have released no further details at present.
The accident is the latest in a number of incidents this year involving rail cars carrying toxic chemicals and will likely bring further pressure for rail operators to upgrade their aging fleets to more robust, double-reinforced, models to prevent disasters.