As federal investigators worked to find out why a 150-car train derailed in northeast Ohio, the state’s governor warned late Sunday that unstable temperatures in a car carrying chemicals could lead to an explosion.

The area most at risk of being affected by Friday’s crash, which is within a 1-mile radius of the accident in the village of East Palestine, was evacuated early Saturday and remained off limits, authorities said.

But Gov. Mike DeWine’s office said about 500 residents remained in the 1-mile zone. He said they were subject to an «urgent warning» to evacuate.

«In the last two hours, there has been a drastic change in temperature in a train carriage, and now there is the possibility of a catastrophic failure of the tanker that could cause an explosion with the potential for deadly shrapnel traveling up to a mile,» said the governor. the office said in a statement.

The governor’s office said residents with children who stay behind could face arrest. He cited a threat made by the Columbiana County Sheriff’s Office.

At 8:00 pm, the governor ordered Ohio National Guard troops to move into eastern Palestine to assist local authorities, his office said.

The crash site produced multiple small explosions or bursts of combustion after several cars believed to be carrying hazardous materials blew up in the derailment, reported at 8:55 pm Friday, and continued to burn Sunday morning.

The wreckage included approximately 50 cars off the track, authorities said. National Transportation Safety Board member Michael Graham identified at least 10 of them Sunday as «hazardous materials cars,» or those that transport hazardous materials or chemicals. Five of them were said to be carrying a worrying chemical, vinyl chloride.

A train buff whose backyard overlooks the east-west railroad used by Norfolk Southern said the area of ​​the derailment is a straight section.

Federal investigators have focused in part on the role of a possible mechanical malfunction, authorities said Sunday.

The train crew said an alarm indicating such a malfunction went off just before the accident, Graham told a news conference.

In addition, two videos of the train obtained by NTSB investigators show that one of the cars may have had a broken or malfunctioning axle, Graham said Sunday.

The crew – an engineer, a conductor and a trainee conductor – were able to help stop the train late Friday and then disconnect all three engines from its cars, many of which were on fire, authorities said. No injuries were initially reported.

Vinyl chloride, which is highly flammable, is linked to an increased risk of cancer and can be harmful to health at the level of emitting an odor that humans can smell.

The chemical, which is used to make polyvinyl chloride (PVC) pipes, vehicle upholstery and picnic utensils, has been linked to an increased risk of liver, brain and lung cancer, as well as some types of skin cancer. blood, according to the Centers for Diseases. Control and Prevention.

Environmental Protection Agency personnel have been in eastern Palestine since late Friday and were monitoring air and water, two EPA officials said at Sunday’s news conference.

In a statement on Saturday, the East Palestinian village said that “zero health risks” had been discovered so far.

“The village’s drinking water is safe to drink and is being continuously monitored,” he said.

The NTSB was leading the investigation.