A trio of endangered gray wolves were found dead in southern Oregon and federal officials are offering a $50,000 reward for information about their deaths.

The bodies were found after the collars of two of the wolves put out a “mortality signal” on December 29, prompting a response from state wildlife protection personnel, the US Fish and Wildlife Service announced Friday.

The signals led authorities to the bodies of two collared wolves and one without a collar east of Bly, Oregon, the agency said. No details were provided on how the wolves died.

The reward is being offered for information that leads to an arrest, criminal conviction or civil penalty assessment related to the animals’ deaths.

“The collared wolves were the adult, breeding female OR115 and the subadult OR142 from the Gearhart Mountain Pack,” the release said. The third wolf was also a subadult, or adolescent wolf, it added.

The deaths occurred in an area of “known wolf activity,” that stretches across Klamath and Lake counties, the release said.

Gray wolves that live in the western two-thirds of Oregon are a protected species because they are listed as endangered under the federal Endangered Species Act, according to the Fish and Wildlife Service.

The Oregon Department of Fish and Wildlife said it is aware of just seven wolves remaining in the Gearhart Mountain pack, including the breeding male.

CNN has reached out to the US Fish and Wildlife Service for more information about the circumstances of the deaths.

Anyone with information about the case should contact the federal agency or Oregon State Police, the service said.