Tens of thousands of minks on a central Minnesota farm were set free from their cages, unleashing the prized fur-bearing creatures into the dark of night, authorities said.

"These nitwits think they are doing something good," Stearns County Sheriff Don Gudmundson said Monday, about a half-day after people he's convinced are among militant animal rights advocates sneaked onto Lang Farms near Eden Valley sometime between 10:30 p.m. Sunday and 5:30 a.m. Monday.

The Sheriff's Office put the value of the minks at more than $750,000.

"Some of the mink are dying from the stress or something else, we don't know," the sheriff said. "A large number will starve to death. They weren't taught to hunt by their mother. Others will get run over on the road."

The farm has a "number of people out there with nets, capturing some of them," Gudmundson said midafternoon Monday. "The mink don't know where to go. They've never been out of their cages."

Along with the risk of biting humans, Gudmundson said there is concern for any wildlife that come into contact with any of the minks, a species known for its angry disposition. If anyone comes upon a mink, authorities are warning the public not to approach the animal because it can bite.

The release happened next to wildlife management and wilderness preservation areas, leading the Sheriff's Office to alert state and federal authorities of the predatory animals' potential to "have a negative impact on the surrounding native wilderness preservation area."

"They can travel for miles and miles and miles," Gudmundson added.

Gudmundson was emphatic in pinning the blame on animal rights radicals, who have had a history of these types of acts as part of their mission to undermine the mink industry.

"Who else is going to do this?" the sheriff said.

Given that fencing was dismantled around the barns and every last mink was freed from their cages, Gudmundson concluded that multiple suspects were involved and remain at large.

Lang Farms wants anyone who spots any of the animals to call the operation at 1-320-453-4750 so its personnel can capture them.

Anyone with information about the mass release is urged to call the Sheriff's Office at 1-320-251-4240 or Tri-County CrimeStoppers at 1-800-225-1301.

Paul Walsh • 612-673-4482