Three bison were illegally shot and killed along the road that runs through the Blacktail Plateau in Yellowstone. NPS map.

Three bison were shot and killed inside Yellowstone National Park last week, leading park officials Tuesday to ask the public for help in finding the person or persons responsible.

The carcasses were found well inside park boundaries on the Blacktail Plateau to the east of Mammoth Hot Springs. Park officials had been keeping the incident quiet the past few days while investigating the matter.

Authorities were not releasing such details as to whether the bison were butchered (for trophies), the type of firearm used, or how far from Mammoth Hot Springs the killings occurred.

Park rangers determined the bison were likely shot between the evening of March 13 and morning of March 15 alongside the road in the Blacktail Plateau area.

A reward of up to $5,000 is offered for information leading to the arrest and conviction of the individual(s) responsible for the crime. Anyone with information is requested to call the Yellowstone National Park Tip Line at 307-344-2132. You can leave your name and number, or you can remain anonymous.

The Lacey Act and the Code of Federal Regulations strictly prohibit the killing or removal of any animal from inside Yellowstone. This includes animals shot legally outside the park that cross into and die within the park boundary. Taking and removing any animal parts, including shed antlers, is also prohibited.

Violators are investigated and aggressively prosecuted, and are subject to penalties including fines, restitution, and the forfeiture of vehicles, equipment and personal property associated with the violations.

Hunting is illegal within the park's borders, and while it's legal to carry a firearm if you are properly permitted, it is illegal to discharge that firearm.