ROLLA (AP) - Monday's storms in northeastern North Dakota spawned at least six tornadoes, including one with a nearly continuous 18-mile track that hit parts of Belcourt and Rolla.

Survey teams from the Bismarck and Grand Forks offices of the National Weather Service and from Environment Canada made the determinations.

State and local officials say nearly 20 homes are believed destroyed in Rolla and Belcourt, and more than 50 others damaged.

One man was seriously hurt. The brother of Martin Peltier of Belcourt said he is recovering from hip surgery in a Bismarck hospital. Peltier suffered a crushed pelvis and three spinal fractures.

Martin Peltier's home was one of those destroyed, brother Melvin said. "We're trying to salvage anything we can out of it," he said.

Multiple tornadoes are not uncommon during the summer in North Dakota, said Greg Gust, a Weather Service meteorologist in Grand Forks.

"Typically, every year, we're going to have a couple of different days - what we call 'outbreaks' - that we have multiple tornadoes," he said.

The strongest documented storm on Monday was an EF-3 tornado that struck the north side of Rolla. The tornado had estimated wind speeds of 140 mph.

Government and volunteer organizations are making help available to Rolette County residents - everything from donations to cleanup to mental health support.

"The Red Cross is our biggest help right now. They're doing shelter, food and clothing," said Anita Blue, emergency manager for the Turtle Mountain Band of Chippewa.

Blue said not only were homes lost, but the storms uprooted hundreds of trees.

"Trees are sacred to native people because they're used in ceremonies," she said. "To us, they have a great value."