PORTLAND, Ore. (AP) — An elk hunter killed a wolf in self-defense in northeastern Oregon, the first time that's happened since the predator began migrating to the state in the late 1990s, state police said Thursday.

The Union County district attorney accepted the hunter's explanation of the Oct. 27 shooting, and the 38-year-old man from Clackamas won't be prosecuted, Capt. Bill Fugate said. In Oregon, it's illegal to kill a wolf for sport.

The hunter told investigators he was alone when he saw three animals he believed to be coyotes, Fugate said. One of them ran toward him, forcing him to shoot. The animal died from a single shot, and the others ran away.

The hunter said he returned to camp and told fellow hunters what happened. He said he was unsure if he shot a coyote, so he returned to the scene and discovered it was a wolf.

The hunter, whose name has not been released, reported the shooting.

Investigators determined the wolf was 27 yards away when the hunter fired, Fugate said.

The Oregon Department of Fish and Wildlife determined the wolf was an 83-pound female associated with OR-30, a male wolf known to live in the Starkey and Ukiah wildlife management units in Union County.

In 2016, wildlife officials estimated a minimum of 112 wolves lived in Oregon in 11 packs that included eight breeding pairs. It's illegal to kill a wolf except in self-defense, although lethal action can be approved if an animal is observed repeatedly killing livestock.

The Oregon Department of Fish and Wildlife said dangerous encounters between wolves and people are rare, and this is the first time since wolves returned to Oregon that one has been killed in self-defense.

"They will usually avoid humans and leave the area when they see, hear, or smell people close by," Roblyn Brown, the agency's acting wolf coordinator, said in a news release. "If you see a wolf or any other animal and are concerned about your safety, make sure it knows you are nearby by talking or yelling to alert it to your presence. If you are carrying a firearm, you can fire a warning shot into the ground."