Two Minnesota women have been attacked while swimming by otters, within the last month.

The two separate attacks occurred in lakes about 60 miles apart and are considered unusual by experts, reported the Star Tribune.

Carol Schefers, 38, was the most recent attack victim. Schefers was swimming in Ude Lake last weekend when she was attacked by two otters and was bitten 18 times.

Schefers was taken to a nearby hospital and given antibiotic, rabies, and tetanus shots.

Leah Prudhomme was also attacked by an otter last month in Duluth while training for a triathlon. Prudhomme was bitten 25 times, leaving her wet suit shredded.

Animal experts find the attacks surprising, reported Minnesota Public Radio.

George Parsons, director of fishes at Shedd Aquarium in Chicago, said “the number of bites per victim is a little bit astounding to me.”

"Usually they'll bite three or four times and then kind of give up,” Parsons said.

Parsons told MPR that swimmers who spot an otter should be as loud as possible and avoid areas where they see otters with young pups.