A smoldering tangle of dozens of derailed freight cars, some carrying hazardous materials, has kept an evacuation order in effect in Ohio near the Pennsylvania state line as environmental authorities warily watch air quality monitors.

About 50 cars derailed in East Palestine at about 9 p.m. Friday as a train was carrying a variety of products from Madison, Illinois, to Conway, Pennsylvania, rail operator Norfolk Southern said. No injuries to crew, residents or first responders have been reported.

East Palestine officials said Sunday that emergency responders were monitoring but keeping their distance from the fire, saying remediation efforts could not begin as long as the cars smoldered. The evacuation covers a a 1-mile (1.6-kilometer) radius, officials said.

Mayor Trent Conaway, who declared a state of emergency in the village, said one person was arrested for going around barricades right up to the crash during the night. He warned that more arrests would follow if people did not to stay away.

“I don’t know why anybody would want to be up there; you’re breathing toxic fumes if you’re that close,” he said, stressing that monitors of air quality away from the fire showed no levels of concern and the town’s water is safe because it is fed by groundwater unaffected by some material that went into streams. Environmental protection agency crews were working to remove contaminants from streams and monitor water quality.

Fire Chief Keith Drabick said it was so important to avoid the area “because a train carrying hazardous material wrecked in the town and is burning. Doesn’t get any simpler than that.”

Sheriffs went door-to-door Sunday to count residents remaining and urge people within the evacuation area to leave. “We are asking residents to please evacuate and cooperate,” officials said in a statement. Schools and village offices will be closed Monday and officials would determine that afternoon whether the school closure would be extended.

Norfolk Southern said 20 of the more than 100 cars were classified as carrying hazardous materials — defined as cargo that could pose any kind of danger “including flammables, combustibles, or environmental risks.” Some cars carried vinyl chloride, and at least one was “intermittently releasing” its contents via a pressure release device.

The National Transportation Safety Board said only 10 cars carrying hazardous materials derailed and five of them were carrying vinyl chloride, not 14 as was said earlier. And officials stressed again late Saturday that they had not confirmed the release of vinyl chloride other than from pressure release devices operating as designed.

Vinyl chloride, used to make the polyvinyl chloride hard plastic resin in a variety of plastic products, is associated with increased risk of liver cancer and other cancers, according to the federal government’s National Cancer Institute. Norfolk Southern was to provide a fact sheet listing all chemicals involved.

The evacuation order covered homes of 1,500 to 2,000 of the town’s 4,800 to 4,900 residents, but officials said it was unknown exactly how many were actually affected. About eight residents remained at an emergency shelter. Norfolk Southern opened an assistance center in the village to gather information from affected residents; village officials said 75 people went to the center Saturday and about 100 had been there Sunday morning.