“All the mink at the farm, (in Umgransele, northern Sweden), around 2,500, were released,” police spokesman Ingemar Bålhammar told AFP.
While police said the animals were deliberately released, they had “no idea” who was responsible.
Some of the mink however did not enjoy freedom for long. As they dispersed into the surrounding countryside, some fled into woods while others made their way to a nearby motorway.
“A large number, at least 50, were hit and killed by cars,” Bålhammar said.
The owner of the farm was on Friday attempting to recover the remaining animals from the surrounding area.
Thousands of mink were released from the same farm in March and August 2002. While police questioned animal activists at the time, no charges were brought.