Fearing an explosion, officials release toxic chemical after Ohio train derailment

Officials on Monday completed the release of toxic chemicals that had been carried on a train that derailed over the weekend in eastern Ohio. Officials had warned that the chemical could be deadly if inhaled.

The release of vinyl chloride, a toxic, flammable gas used to produce vehicle interiors and PVC piping, was completed late Monday afternoon after evacuations were expanded from East Palestine, Ohio, the site of Friday night's derailment, to an adjacent community in Pennsylvania.

The release was "successfully completed," according to the train's operator, Norfolk Southern. A burn-off of material would continue past nightfall, it said.

A federal Emergency Alert System message on Monday urged residents in East Palestine and Pennsylvania's Darlington Township to leave immediately.

The office of Ohio Gov. Mike DeWine said Sunday night 500 people had defied orders to leave, but on Monday he said he believed all had left.

The Ohio National Guard was deployed to the area late Sunday, and authorities went door to door urging stragglers to move out, DeWine said at a news conference Monday.

"Those in the red area are facing grave danger of death if they are still in that area," he warned.

Two of five train cars believed to be carrying vinyl chloride were likely to have been filled with the gas, and temperature changes could have set it off, officials said at the news conference.

That left leaders with two bad choices: release a gas known for its deadly potential if inhaled and associated with a higher risk of cancer or stand back for an extended period of time with the potential for an explosion.

Authorities said an explosion would come with two dangers, including the same one that comes with a controlled release, exposure to a hazardous material.

"The vinyl chloride contents of five rail cars are currently unstable and could potentially explode, causing deadly disbursement of shrapnel and toxic fumes," DeWine said.

Both of cars believed to be filled with vinyl chloride contained 177,000 pounds of the chemical, a National Guard official said. It was not clear how much was in the others. All five were subject to the controlled release and subsequent burn off, officials said.

"We’re going to place a small-shaped charge. It’s going to create a hole about 2 to 3 inches into the tank car," said Scott Deutsch, a hazardous materials regional manager for Norfolk Southern. "This will allow the material to come out of the tank car."

Environmental Protection Agency personnel have been in East Palestine since Friday night, and they were monitoring air and water, with no sustained signs of toxicity for East Palestine, agency officials said Monday.

A state environmental safety official said that runoff from the train's subsequent fire and firefighting efforts reached a natural waterway that but officials stemmed the flow. Fish in the area were affected, the official said.

The derailment was reported at 8:55 p.m. Friday as the 150-car train was headed from Matteson, Illinois, to Conway, Pennsylvania. It was estimated that 50 cars were off the track.

No injuries were reported, including among the train's three-person crew.

Initial observations from the National Transportation Safety Board, which is leading the investigation, include video and inspection evidence of a broken axle on one of the cars, a board member said Sunday.

This article was originally published on NBCNews.com