Officials fear explosion near Ohio train derailment site

A rail car at the site of a train derailment in the US state of Ohio was at the risk of a deadly explosion that could shoot shrapnel up to a mile away, authorities said.

A mandatory evacuation order is in place for anyone living within the one-mile (1.6km) radius.

At least 50 cars of the train carrying hazardous material derailed on Friday setting off a blaze.

"There is a high probability of a toxic gas release," the local sheriff warned.

Officials from the National Transportation Safety Board said there were 20 hazardous material cars on the train, 10 of which derailed near East Palestine, Ohio. Five of the derailed cars carried a chemical known as vinyl chloride, which NTSB officials said were released through pressure release devices.

Officials warned of the potential of "a catastrophic tanker failure" after a "drastic temperature change" was observed in that rail car, according to a statement from Ohio Gov. Mike DeWine's office.

A shelter-in-place order also went into effect for the entire town over concerns about chemicals possibly spilling into the air.

"While most individuals in the one-mile (1.6km) radius have already evacuated," Ohio Governor Mike DeWine Tweeted on Sunday, "local officials say more than 500 people have declined to leave their homes."

Mr DeWine asked those who have not left yet to "immediately evacuate".

On Sunday, sheriffs went door-to-door to count residents remaining and urge people within the evacuation area to leave.

"We will be enforcing the evacuation zone," Sheriff Brian McLaughlin of Columbiana County said in a statement on Facebook. "Please, for your own safety, remove your families from danger."

Schools and village offices will be closed at least through Monday, and businesses within the evacuation zone are not allowed to open Monday, officials said.

The cause of derailment for the Norfolk Southern train, which carried 100-plus cars, remains unknown. It had departed from Madison, Illinois, and was bound for Conway, Pennsylvania, when it derailed, according to the NTSB.

Harmful levels of the chemical have not been detected in the community, state environmental officials said.

Exposure to vinyl chloride, a type of gas, has been associated with heightened risks of certain forms of cancer, according to the National Cancer Institute.

The mayor of East Palestine, a town of roughly 5,000, said he did not know when shelter-in-place orders would be lifted.

Two evacuation stations have opened to provide shelter to residents, CNN reported.

NTSB officials said it will take roughly four to six weeks for the NTSB to have a preliminary report on the accident.