U.S. regulators joined the investigation into a fiery CSX Corp. oil-train derailment in West Virginia that forced residents to flee their homes in frigid weather and threatened drinking water.

The crash, the second in 10 months involving a CSX train laden with Bakken oil, promises to add to the public-safety debate over North American crude-by-rail shipments. The Obama administration is revising standards after a series of oil-train derailments led by a 2013 Quebec accident that killed 47 people and non-fatal explosions in the U.S.

Sarah Feinberg, acting administrator of the Federal Railroad Administration, and Chief Safety Officer Robert Lauby were traveling to the crash site, and investigators from the Pipeline Hazardous Materials Safety Administration were already on the scene, according to the FRA.

As firefighters worked Tuesday to douse the remaining flames following Monday’s derailment, authorities’ focus turned to learning why the train came off the tracks and whether the cargo of North Dakota Bakken crude had reached a municipal water intake on the Kanawha River.

Ice dams may have kept the crude from reaching a local water system, and authorities are testing samples to be sure the spill was contained, said Terrance Lively, a spokesman for the West Virginia Department of Military Affairs and Public Safety in Charleston.

Oil, Water

“We do know there is some crude oil in the stream,” Lively said Tuesday by telephone.

Gary Sease, a CSX spokesman, didn’t immediately respond to a request for comment Tuesday about track conditions and the train’s speed at the time of the accident, which occurred after 1 p.m. on Monday.

The rural nature of the crash site may have limited the fallout from having 27 oil cars derail and as many 15 of them catch fire. Even with power lines damaged, the possible jeopardy to the water system and Governor Earl Ray Tomblin declaring a state of emergency covering Kanawha and Fayette counties, only about 85 people had to use local shelters, Lively said.

CSX is cooperating with federal authorities, Sease said by e-mail. The train — with 107 oil cars, two cars of sand and a pair of locomotives — was headed for Yorktown, Virginia, according to Sease.

The destination was a rail-to-marine terminal operated by Plains All American Pipeline LP, according to New York-based ClipperData, which tracks waterborne crude movements. A Plains All American spokesman, Brad Leone, didn’t immediately respond to a voice message and e-mail left before regular business hours Tuesday.

Lynchburg Incident

The April 2014 crude-train derailment in Lynchburg, Virginia, also involved a CSX train headed to the Plains All American facility. About 15 cars came off the tracks, and the resulting fire led to dramatic video of flames and billowing smoke against the backdrop of a small city’s downtown.

The tank units on the West Virginia train were CPC-1232 rail cars made with either 7/16-inch (1.1-centimeter) carbon steel shells and 1/8-inch carbon steel jackets, or cars with 1/2-inch carbon steel shells, according to an e-mail from Sease.

The new U.S. standards for trains carrying crude would first require companies to upgrade tank cars known as DOT-111s, which safety investigators have said are prone to puncture in rail accidents, a person familiar with the proposal said this month.

Draft Rule

The draft rule also would require that new cars be built with steel shells that are 9/16th of an inch thick, people familiar with the plan said. The walls of the current cars, both DOT-111s and the newer CPC-1232 models, are 7/16th of an inch thick.

Monday’s derailment was the second in three days in North America. Canadian National Railway Co. shut its main line linking western and eastern Canada after an eastbound train carrying crude oil came off the tracks in Ontario.

The train of 100 cars, all carrying crude from Canada’s oil-producing region of Alberta to eastern Canada, derailed just before midnight Saturday in a remote and wooded area about 30 miles (48 kilometers) north of Gogama, Ontario, spokesman Patrick Waldron said in an e-mail.

–With assistance from Theo Mullen in Atlanta, Rebecca Penty in Calgary, Aaron Clark in Tokyo, Jim Polson in New York and Dan Murtaugh in Houston.