CNN —
As residents are urged to flee, teams at the site of a burning derailed train in East Palestine, Ohio, are working to prevent a “catastrophic tanker failure” and explosion that could shoot deadly shrapnel up to a mile away, officials said.
The train was carrying hazardous materials when it derailed Friday, igniting a massive inferno and prompting evacuations and shelter-in-place orders amid concerns over air and water quality. As the fire burned for a third night Sunday, the threat escalated, and officials pleaded with those who remained in their homes in the 1-mile radius around the crash site to evacuate quickly.
“There is a high probability of a toxic gas release and or explosion,” Columbiana County Sheriff Brian McLaughlin warned. “Please, for your own safety, remove your families from danger.”
The explosion risk comes from an extreme temperature change inside one of the Norfolk Southern rail cars, warned Gov. Mike DeWine, who on Sunday sent the Ohio National Guard to the scene.
A “drastic change” was detected Sunday in a chemical – vinyl chloride – that officials had been concerned about, Fire Chief Keith Drabick said. Five of the derailed cars were carrying the substance, said the National Transportation Safety Board, which is investigating the disaster.
A man-made chemical used to make PVC, vinyl chloride burns easily at room temperature, and breathing high levels of it can make someone die or pass out if they don’t get fresh air, the Ohio Department of Health said. It also can cause dizziness, sleepiness and headaches and has links to increased risk cancer in the liver, brain, lungs and blood.
“We are at a risk now of a catastrophic failure of that container. … Measures are being taken to try and control that and prevent that from happening,” Drabick said. “This catastrophic failure, if it occurs, it will produce hydrogen chloride and phosgene gas into the atmosphere” and the risk radius around the derailment may grow.
“We need you to leave now,” he told some 500 residents who had declined to leave while most of their neighbors evacuated.
While air and water quality remained stable Sunday, “things can change at any moment,” James Justice of the EPA’s Emergency Response warned.
Air and drinking water were safe, East Palestine Mayor Trent Conaway had assured residents. Still, Monday classes at East Palestine schools and city meetings are canceled, he said, and a shelter-in-place order is in effect in the whole town of roughly 5,000 people near the Pennsylvania border, about 20 miles south of Youngstown, Ohio.
There was a mechanical failure warning before the crash, NTSB Member Michael Graham said Sunday afternoon at a news conference. About 10 of 20 cars carrying hazardous materials – among more than 100 cars in all – derailed, the agency said.
“The crew did receive an alarm from a wayside defect detector shortly before the derailment, indicating a mechanical issue,” Graham said. “Then an emergency brake application initiated.”
Investigators also identified the point of derailment and found video showing “preliminary indications of mechanical issues” on one of the railcar axles, Graham said.
NTSB is still investigating when the potential defect happened and the response from the crew, which included an engineer, conductor and conductor trainee, Graham added.
Investigators have also requested records from Norfolk Southern, including track inspection records, locomotive and railcar inspections and maintenance records, train crew records and qualifications, Graham said.
Rail travel is recognized as the safest method of transporting hazardous materials in the US, according to the US Department of Transportation’s Federal Railroad Administration.
“The vast majority of hazardous materials shipped by rail tank car every year arrive safely and without incident, and railroads generally have an outstanding record in moving shipments of hazardous materials safely,” the administration said.
Since the fire in Ohio is still burning, investigators haven’t been able to walk around the crash site.
It’s unclear how long it’ll take before the scene is cleaned up, Graham said, adding, “We still have a hot zone in there.” The preliminary report on the derailment is expected in four to six weeks, he added.
