The floods that began Tuesday continued to wreck havoc in the city Wednesday, the Duluth (Minn.) News Tribune reported. Rescue squads helped evacuate about 50 people by airboat.
Rescuers also saved an 8-year-old boy who was swept up by flooding for five blocks. He suffered no major injuries.
Most residents in flooded areas have evacuated their homes, but a few people remain. Health officials advised the residents staying behind not to use tap water for fear of contamination.
Minnesota Gov. Mark Dayton planned to visit Duluth Thursday.
"This morning my thoughts are with our friends and neighbors in Duluth and the surrounding region, as they respond to major flooding," Dayton said in a statement. "I have spoken to Duluth Mayor Don Ness and have offered all possible state assistance now and during the recovery."
"People need to be extremely careful in these kinds of dangerous conditions," Tom Crossman, captain of the St. Louis County Sherriff's Volunteer Rescue Squad said. "This is far worse than anything we've ever seen before."