WAUPACA, Wis. -- State wildlife officials said that a group of snowmobilers ran over five deer, killing four of them and severely injuring a fifth in what a warden calls a senseless act of cruelty.

State Department of Natural Resources warden Ted Dremel said on Monday no arrests have been made in the incident that occurred early Saturday morning about five miles south of Waupaca.

Dremel said that he believes three or four snowmobiles were involved in what amounted to a roundup of deer in a farm field. Dremel said one deer was left tied to a tree and choked itself to death. Another deer had broken legs and was euthanized.

Dremel said five miles of snowmobile trails in area have been closed due to the carnage. Some snowmobile clubs have offered $4,000 in rewards for information leading to the arrest of those responsible.