Game wardens assisted by Yellowstone National Park rangers killed five bull bison Thursday near Gardiner, just outside the park boundary, the Montana Department of Fish, Wildlife and Parks said.

Attempts to send the bison into the park by hazing them didn't work, said Cheryl Matthews, a Yellowstone information officer. She said another 18 bison were lingering near the park border at Gardiner and it was possible that on Friday rangers would try hazing to get them into the park.Earlier this week, wardens killed two other bison in the same area.

All seven carcasses will be auctioned in Bozeman on Friday, said Bernie Kuntz, a spokesman for the state wildlife agency.

Montana's interim bison management plan calls for bison to be killed if they leave the park and enter private land and landowners complain.

If bison leave the park but stay on public land, do not approach cattle and do not cause problems, they are allowed to live, according to the policy. About 200 bison are outside the park near West Yellowstone.