Three people have been airlifted to a hospital after their canoe plummeted over a waterfall near the U.S.-Canada border in northern Minnesota.

The Lake County Sheriff's Office says one teen boy had to be rescued from under a log where he became wedged after the dramatic plunge over the Upper Basswood Falls in the Boundary Waters Canoe Area Wilderness around 1 p.m. Tuesday.

Sheriff Casey Johnson says the waterfalls are 25 to 30 feet tall.

It took a couple of hours to rescue the boy, and the sheriff's office says he likely has hypothermia and an ankle fracture. The boy's name was not released.

A Minnesota State Patrol helicopter flew all three canoeists to a hospital in Ely, about 100 miles north of Duluth.