YAKIMA, Wash. — Yakima police killed one dog, wounded another and were continuing to search for a third Wednesday that attacked an officer and later severely mauled a man walking his own dog.

The dogs, described as pit bull mixes, bit the officer several times in the leg after he responded to reports of aggressive strays in the 100 block of Division Street by employees of the Del Monte plant at 10:45 p.m. Tuesday.

The officer drove the dogs off with pepper spray and was treated for bite wounds at a local hospital and released. The officer, whose name was not released, is expected to return to work next week.

Hours later, shortly before 4 a.m., the same pack attacked a man as he walked his border collie along railroad tracks in the same area, police said.

An employee of a nearby business heard the man’s cries for help and was able to drive the dogs off by throwing large rocks at them and striking them with a wooden post.

The 48-year-old victim, who also was not identified, was taken to a local hospital with numerous bite wounds to his head, face, arms, torso and legs. Police described his injuries as severe, but said he and his dog are expected to survive.

Following the second attack, a team of seven officers began hunting the dogs on foot. They shot two of them, one fatally and gave one a probable fatal wound based on a blood trail in the area.

However, the wounded dog ran from the area with the third dog, a tan pit bull mix that weighs about 25 to 30 pounds. The dogs remain at large.

The public is being urged to be cautious in the area, particularly in southeast Yakima neighborhoods as police and animal control officers search for the animals.

In Yakima, pit bulls have been banned as a breed since a series of attacks in 1996. Even so, attacks involving the breed crop up periodically.

In 2007, a pit bull attacked a child on North 24th Avenue despite neighborhood complaints about the dog. In 2004, five pit bulls were seized from a home on North Naches Avenue after they mauled a 15-year-old boy. The dogs belonged to the boy’s mother’s boyfriend.

Lt. Nolan Wentz, a spokesman for the Yakima Police Department, said the dogs appeared to be wild. They had no collars and appeared to be living in the area along the tracks.

“That might be why we didn’t hear about them until now,” he said. “There aren’t any residents there.”