Move aside, grizzly bears and mountain lions. River otters in Whitehall, east of Butte, Mont., attacked four people swimming in the Jefferson River July 11, and the victims have wounds and a 21-day series of rabies shots to prove it. Mike Hannegan of San Francisco, Calif., said he was attacked by an otter 12 times while trying to help his son, Kevin, escape from the animal. The Hannegans each received more than 20 stitches for gashes in their arms, and Kevin also suffered cuts on his head and gashes in his life jacket. Three hours later, Tina Smith of Whitehall was swimming in the river when an otter chewed through her shoe. The otter also bit Smith's step-daughter, Penny Young, and repeatedly bloodied her shin with puncture wounds. Smith and Young said they saw two otters but weren't sure if one or both attacked them. State Game Warden Jim DeBoer says the muscular, weasel-like creatures are common in the area but aggressive behavior is not. "Some of the local dogs are a much bigger threat than all of the otters put together," he said. DeBoer said that after the attacks, someone shot and killed an otter when it hissed and snapped aggressively. DeBoer says the otter corpse is being tested for disease.