An attempt by U.S. animal-rights activists to free minks from an Ontario fur farm ended in disaster when 300 of the 1,500 animals died from exposure and stress after being released.

Another 30 were hit by cars on nearby roads, and an unknown number were killed fighting among themselves.

Most of the surviving animals were caught in a wild, early-morning chase. “They don’t understand what they’ve done,” said ranch owner Bill McLellan of the five activists who were arrested in conjunction with the incident. “They thought they’d live happily ever after, but these are very domesticated.”

Minks are normally in hibernation at this time of the year, McLellan said.