(CNN) -- A string of tornadoes raked through southeastern North Dakota and into west central Minnesota on Saturday night.
Most of the damage was in Richland County, North Dakota, according to Greg Gust, warning coordination meteorologist with the National Weather Service.
"We know of at least three distinct tornadoes that formed in this, possibly more," he said. None of them hit any towns, he said, "although the community of Campbell, Minnesota was very close to being hit."
One of the tornadoes was on the ground for at least 30 minutes. Gust said a typical tornado might last only three to five minutes.
"So to have ones that are tracking for 10 to 15 miles or more are a bit rare, and to have one that's 30 minutes or longer on the ground, that's a pretty sizable and strong tornado," Gust said.
"We do have two farmsteads that were hit pretty hard, one with the house destroyed," he said. "The residents there were in the basement. They are safe. Another farmstead had significant damage on it. No one was home."
The National Weather Service doesn't know yet how strong the winds from the tornadoes were, but the wind was strong enough to break off power lines and damage homes.
"We're aware that one home was pretty much destroyed," Gust said. "So clearly, we're dealing with wind speeds in excess of 100 mph."
The weather service will send a crew to the area Sunday to meet with emergency management officials to assess the damage.