BILLINGS, Mont. -

Montana livestock officials say two bison were shot and killed after repeated efforts to drive them back into Yellowstone National Park to make way for cattle failed.
    
Department of Livestock Executive Officer Christian Mackay says the bull bison shot Wednesday in the West Yellowstone area included one on private land and one on U.S. Forest Service land.
    
State and federal agencies have a no-tolerance policy for bison outside the park for much of the year to keep them away from cattle.
    
The goal is to prevent transmissions of the disease brucellosis to livestock, although no such cases have been reported in the wild.
    
Brucellosis was first brought to the region through the diseased livestock of European settlers. It has since been eradicated across most of the U.S.