Two wolf pups killed on Ninemile Road last week were hit by a car or truck, possibly while their parents were away hunting for food, federal officials said Wednesday.

But the investigation continues into the pups' deaths, as it is illegal to kill a threatened species.

"Law enforcement would like to talk to the person who may have hit these wolves," said Ed Bangs, the U.S. Fish and Wildlife Service's wolf recovery coordinator. "We'd like to see how it happened."

It may be that the wolves were playing in the road and were not seen by an approaching motorist, Bangs said. "Maybe they were just playing around while the adult wolves were out hunting. Or maybe one pup got run over, and the other one was checking it out."

If the deaths were "purely accidental," the motorist would not be prosecuted, he said. "But we want to know the circumstances."

Karen Miranda, a public affairs specialist in the agency's Denver office, added that the Endangered Species Act does not require humans to put themselves at risk to save the life of an at-risk species. And that could include swerving to miss animals.

Another pup from the same litter was hit and killed in the same spot on July 20. The young wolves were all about 4 months old.

"Highways are tremendous killers of wildlife, and wolves are no exception," Bangs said. "The numbers are just staggering. A few years ago, the alpha female of the last breeding pack of wolves in Banff was killed on the highway."

Three adult wolves have been killed in the Ninemile this year by federal agents trying to stop a rash of llama depredations in the lower part of the valley. But Bangs said he doesn't believe there is any link between the road-kills and the llama troubles.

"These are two separate problems," he said. "Hopefully, people can remember to slow down for wildlife on the road. And our law enforcement guy would like to talk to someone if they think they may have run over a wolf."

The pups were killed on upper Ninemile Road, near where the property ownership changes from private to public land. Anyone with information about the incident should contact special agent Rick Branzell of the Fish and Wildlife Service office in Missoula, at 329-3000.