Two-thirds of the residents were advised to evacuated a southeastern North Dakota town overnight after a train carrying crude oil derailed and exploded, and officials warned that acrid smoke could blow into the area.

No one was hurt in Monday’s derailment of the mile-long train that sent a great fireball and plumes of black smoke skyward about a mile from the small town of Casselton.  The fire had been so intense as darkness fell that investigators couldn’t even get close enough to count the number of burning cars.  Some burned through the night.  The National Transportation Safety Board was preparing to investigate.

The Cass County Sheriff’s Office called on the 2,400 people living in Casselton, about 25 miles west of Fargo, to leave their homes, citing a shift in winds blowing smoke toward the town. Health experts were testing the quality of the air but did not yet have results early Tuesday.

Much of Casselton’s water tower was covered in soot and as the day progressed a lot of the black powder was witnessed around town.

Sheriff’s Deputy Joe Crawford said about two-thirds of the town’s residents had heeded the recommendation to evacuate their homes.  Officials were waiting for daybreak, this morning, before making new attempts to investigate the scene.  The fire died down overnight, “but we’ve still got plenty of smoke and plenty of fire and plenty of heat,” Crawford said.

Terry Johnson, the manager of a grain dealer less than a mile from the derailment, said he heard at least six explosions in the two hours following the derailment.

Official estimates of the extent of the blaze varied.  BNSF Railway Co. said it believed about 20 cars caught fire after its oil train left the tracks about 2:10 p.m. Monday.  The sheriff’s office said Monday it thought 10 cars were on fire.  Officials said the cars would be allowed to burn out.

Authorities haven’t yet been able to untangle exactly how the derailment happened.  BNSF spokeswoman Amy McBeth said another train carrying grain derailed first, and that this knocked several cars of the oil train off adjoining tracks.

BNSF said both trains had more than 100 cars each.

The incident will likely prompt discussion about the safety of transporting oil by cross-country rail.  Fears of catastrophic derailments were particularly stoked after a train carrying crude from North Dakota’s Bakken oil patch crashed in Quebec last summer.  Forty-seven people died in the ensuing fire.

The National Transportation Safety Board said Monday night it had launched a “go-team” to investigate this latest derailment.

It’s fortunate that the derailment did not happen within the city limits of Casselton, because the railroad tracks run straight through town.

A shelter was set up in nearby Fargo, North Dakota due to the fact that some residents needed shelter since temperatures were expected to dip to 20 below, overnight.  Only 19 people stayed at the shelter Monday night, while most residents found temporary shelter with friends and family, or obtained motel and hotel rooms in the surrounding area.

The North Dakota Department of Health warned that exposure to burning crude could cause shortness of breath, coughing and itching and watery eyes.  It had said those in the vicinity with respiratory conditions such as asthma, bronchitis, or emphysema should minimize outdoor activity.

North Dakota is the No. 2 oil-producing state in the U.S., trailing only Texas, and a growing amount of that is being shipped by rail.  The state’s top oil regulator said earlier this month that he expected as much as 90 percent of North Dakota’s oil would be carried by train in 2014, up from the current 60 percent.

The number of crude oil carloads hauled by U.S. railroads surged from 10,840 in 2009 to a projected 400,000 this year.  Despite the increase, the rate of accidents has stayed relatively steady.  Railroads say 99.997 percent of hazardous materials shipments reach destinations safely.

These types of accidents are likely to occur again due to the administration’s refusal to approve the much requested Keystone Pipeline.

The Keystone Pipeline System is a proposed pipeline system to transport synthetic crude oil from the oil sands of Alberta, Canada, and crude oil from the northern United States, “primarily to refineries in the Gulf Coast” of Texas.  The products to be shipped include synthetic crude oil and diluted bitumen from the Western Canadian Sedimentary Basin in Alberta, Canada, and Bakken synthetic crude oil and light crude oil produced from the Williston Basin (Bakken) region in eastern Montana and western North Dakota.