The governor of the U.S. state of Ohio on Wednesday warned residents living near the site of a toxic train derailment to drink bottled water as authorities investigate potential environmental fallout from the accident earlier this month.

The cargo train derailment in the midwestern U.S. sparked a massive fire and triggered the release of toxic fumes, including from vinyl chloride, a colorless gas deemed carcinogenic by the U.S. National Cancer Institute.

Ohio Governor Mike DeWine told CNN that while air quality in the town of East Palestine where the wreck occurred was "safe," residents should not yet drink the water out of an abundance of caution.

"We did get a test back late yesterday of the water in the village and the first well that we tested, the water was fine," he told the broadcaster, urging people to nonetheless "use bottled water, don't take a chance."

More well results were expected later Wednesday, he said, but Environmental Protection Agency (EPA) Administrator Michael Regan told CNN that testing results from rivers and streams were still being collected and analyzed.

The agency would be able to give the public more information "as the conditions on the ground become safe," Regan said, adding that scientists and engineers would not be put "in harm's way."

The Norfolk Southern train with 150 cars was shipping cargo from Madison, Illinois to Conway, Pennsylvania when it derailed on February 3.

The accident resulted in the derailment of 38 cars, after which "a fire ensued which damaged an additional 12 cars," the National Transportation Safety Board (NTSB) said in a statement Tuesday.

Of the derailed cars, 11 were carrying hazardous materials, including vinyl chloride, butyl acrylate and other chemicals, the NTSB said.

'Very toxic materials'

Five days after the derailment, evacuated residents were allowed to "safely return home," the governor's office said, adding that there would be ongoing air monitoring in the area.

However, a week after the accident, the EPA reported that the chemicals involved in the wreck were "known to have been and continue to be released to the air, surface soils, and surface waters."

Some 3,500 fish died along 12 kilometers of nearby streams, the Ohio Department of Natural Resources reported.

DeWine said Norfolk Southern would be held accountable and should "pay for everything," adding that some people in East Palestine were concerned the company would leave before the cleanup is finished.

"They are responsible for a very serious train wreck that occurred with some very toxic material," he told CNN. "So we're going to hold their feet to the fire."

Norfolk Southern said in a statement Wednesday it had provided $1.5 million to families and businesses for "costs related to the evacuation."

Railroad union officials said they have been warning that such an accident could happen because railroad cost-cutting harmed safety measures, Reuters reported.

"No one wants to listen until we have a town blown off the face of the Earth, then people listen," Clyde Whitaker, chairman and director of the Ohio State Legislative Board for the International Association of Sheet Metal, Air, Rail and Transportation Workers Transportation Division, told Reuters.

(With input from agencies)