A freight train carrying the highly toxic chemical benzene has derailed in the Czech Republic, sparking a huge fire.

Several tankers and a locomotive were ablaze, with firefighters from several regions and a mobile chemical laboratory deployed to the area, according to local media. A massive cloud of dense black smoke was visible for several kilometres.

Railway officials say nobody was injured in the incident, which occurred near Hustopeče nad Bečvou, 50km (31 miles) south-west of the Polish border, on Friday.

Benzene, which is a cancer-causing substance for humans, is an element present in aircraft fuel.

The train “split apart” and subsequently derailed, according to initial reports. A nearby electric substation also caught fire, killing power to the nearby town of Hustopeče.

Flames up to 20m high were visible when the fire broke out, one eyewitness told the Lidove Noviny newspaper.

Dramatic drone footage from the scene, released by the Czech fire service, shows several badly charred and destroyed tankers – some still burning as thick black smoke spews into the sky.

Firefighters used heavy foam to prevent the fire from spreading further, while other tankers were hosed down to prevent more explosions.

A helicopter was also deployed, as well as a special chemical monitoring mobile lab. It took several hours to bring the fire under control, officials said.

The fire affected around 15 of the 17 benzene tanks the train had been transporting, a fire department spokesperson told local media.

“The substance should be the same in all tankers, the amount will be specified, but it is approximately 60 tonnes in one tanker. However, this does not mean that everything will burn out or leak,” Lucie Balážová said.

Locals have been told to stay indoors and not open windows or doors. Officials say air quality “has not yet exceeded” any pollution limits, according to Czech news website iDNES.

Police say they will investigate the cause of the derailment.

Benzene is a colourless or light-yellow liquid with a sweet smell that can evaporate very quickly. It is used in common substances like plastic, resin, nylon and some forms of dyes, pesticides or detergents. It is very flammable.

Exposure to benzene through breathing or ingestion can cause symptoms like drowsiness, dizziness, tremors, vomiting or sleeplessness.

Very high levels of exposure can lead to unconsciousness or death, according to the CDC. Long-term exposure of a year or more could cause issues with blood, bone marrow or the immune system.