An otter attacked Leah Prudhomme while she trained for a triathlon in Island Lake near Duluth, Minn. (KSTP/ABC News)

A Minnesota woman says she was bitten 25 times by an otter that sank its fangs into her flesh as she swam in a lake.

"It just kept coming after me," Leah Prudhomme, 33, of Anoka, Minn. told the StarTribune. "You never knew where it was going to bite next."

Prudhomme, a triathlete, was swimming in Island Lake in northern Minnesota last week when she felt an animal bite her legs. The otter also attacked her feet and back, leaving bite marks as deep as two inches.

The attack lasted seven minutes, according to ABC News affiliate KTSP.

At the time, Prudhomme was training for a triathlon being held at Island Lake next month. She still says she plans to compete in the event.

In the last 20 years, there have been only 40 reported otter attacks on humans in the U.S., most of them in Florida, Ron Moen, of the Natural Resources Research Institute, told Yahoo's Odd News. In 2010, a West Boca, Fla. teen made headlines after f ilming an otter biting him near a lake behind his home.

See more stunning wild animal stories on "20/20: When Animals Strike Back" Friday at 10 p.m. ET.