Half of the oil cars have been separated from the train, but another 56 cars remain in danger, said Cecily Fong, the public information officer with the North Dakota Department of Emergency Services. The collision destroyed both engines on the oil train. Both trains were operated by BNSF Railway Co, which is owned by Warren Buffett's Berkshire Hathaway.
The incident will likely stoke concerns about the safety of shipping increasing volumes of crude oil by rail, a trend that emerged from the unexpected burst of shale oil production out of North Dakota's Bakken fields.
Over two-thirds of the state's oil production is currently shipped by rail.
Initial reports from the scene of the accident did not point to a malfunction on the oil-carrying train. Still, videos of the exploding rail cars are likely to add to the ongoing debate on what fixes are needed as older train cars carry flammable fuels such as oil.
The derailment occurred about a mile west of Casselton, a town of about 2,300 just west of Fargo, between an ethanol plant and the Casselton Reservoir, Fong said.
Casselton is state Governor Jack Dalrymple's hometown.
North Dakota is home to a raging shale oil boom that produced nearly 950,000 barrels of oil a day in October. It is also a major grain producer and long accustomed to a high volume of rail traffic.
But shipments of oil have surged lately, most of it the light, sweet Bakken variety that experts say is particularly flammable.
Trains carried nearly 700,000 barrels a day of North Dakota oil to market in October, a 67 percent jump from a year earlier, according to the state Pipeline Authority.
This summer, a runaway oil train carrying Bakken crude derailed and exploded in the center of the Quebec town of Lac-Megantic, killing 47 people. The incident fueled a drive for tougher standards for such shipments, including potentially costly retrofits to improve the safety of tank cars that regulators have cited as prone to puncture.
In early November, two dozen cars on another 90-car oil train derailed in rural Alabama, erupting into flames that took several days to fully extinguish.
The Association of American Railroads recently proposed costly fixes to older tank cars that do not meet its latest standards but continue to carry hazardous fuels such as oil.
The fixes include protective steel jackets, thermal protection and pressure relief valves, which could cost billions of dollars. Oil shippers, likely to be saddled with the costs of retrofits, oppose some of the changes proposed by the association.
Following the Canadian rail disaster, the U.S. Department of Transportation began an operation it dubbed "Bakken Blitz," which includes spot inspection of oil shipments aboard trains in North Dakota.