According to a preliminary report from the National Transportation Safety Board, as much as 400,000 gallons of crude oil was lost when a BNSF Railway train wrecked near Casselton, N.D. on Dec. 30.

NTSB reported that 21 of the train’s 106 cars derailed after the train collided with a derailed grain train carrying soy beans. Twenty of the oil train’s cars carried crude oil, and 18 of them were punctured. Each car can carry 27,000 gallons of crude oil.

The westbound grain train that crashed first was traveling at about 28 mph when 13 of its 112 cars left the tracks. The eastbound oil train was traveling at about 42 mph when it collided with one of the derailed cars from the grain train.

Both of the trains were operated by BNSF crews. The maximum speed for that section of track is 60 mph.

A damage estimate for the oil train is about $6.1 million. About 1,300 tons of oily dirt had been removed from the crash site by Jan. 13 and sent to an industrial landfill in north-central North Dakota. At least 6,000 more tons of dirt is expected to be removed.

How much of the lost oil was burned and how much went into the soil around the crash site remains to be determined. About 25,000 gallons of crude oil was recovered from the wrecked tanker cars. Crude oil from the Bakken field is considered highly flammable.

The oil train derailment resulted in fiery explosions within sight of Casselton. No BNSF personnel or any of Casselton’s 2,400 residents were injured. About 1,400 residents were temporarily evacuated.