The fire died down overnight, "but we've still got plenty of smoke and plenty of fire and plenty of heat," Sheriff's Deputy Joe Crawford said.
Jeff Zent, a spokesman for Gov. Jack Dalrymple, said the National Guard was on alert if needed.
Laney said much of Casselton's water tower was covered in soot and that he expects to see a lot of the black powder around town as the day progresses.
"Wait until you see the footprints in the snow later on," he said. "That's the stuff coming out of the sky."