(CNN) - A cougar appeared to be stalking two cyclists as they biked over the weekend in the Cascade Mountains near Seattle. Suddenly, the animal charged, a survivor of the animal's attack that killed one told authorities.
The man said he hit the cougar in the head with his mountain bike, and the animal ran into the woods. But as he and the other cyclist were catching their breath and getting back on their bicycles, the animal returned and fastened its mouth on the survivor's head, crunching down, shaking the cyclist side to side like prey, King County Sheriff's Sgt. Ryan Abbott said Sunday, describing the man's account.
The cyclist managed to get loose when the cougar decided to chase his friend, who was running away, according to Abbott.
The two cyclists were attacked along a trail Saturday morning in North Bend, Washington, the King County Sheriff's Office said.
"It's an incredibly tragic story," Capt. Alan Myers of the Washington Department of Fish & Wildlife said Sunday. "It's extremely unusual for a cougar to act this aggressively on humans."
Myers told CNN affiliate KOMO in Seattle that the cyclists did not provoke the attack.
The man who survived is Isaac Sederbaum, 31, said Myers, who identified the deceased as S.J. Brooks, 32.
The King County Sheriff's Office initially said the two cyclists were men. The sheriff's office then on Monday identified Brooks as a woman, using a birth name -- Sonja J. Brooks -- at the request of the cyclist's parents. Brooks went by the pronoun they, according to a bio on the website of the cycling group Friends on Bikes, where Brooks is listed as the Seattle chapter leader. The group's efforts are focused on women of color and trans- and gender-nonconforming people of color in an attempt to increase diversity in cycling.
Brooks was bitten in the face, legs and neck, and Sederbaum's injuries included bite and tear marks and claw scratches on his head, neck and face, Myers said.
Sederbaum underwent surgery and remains in the hospital, according to Abbott. As of Monday, he was in satisfactory condition.
When the cougar released him, Sederbaum jumped back on his mountain bike to get away. As he looked back, he saw the cougar dragging Brooks into the woods, Abbott said.
He rode 2 miles for cellphone reception to call 911, according to KOMO.
When sheriff's deputies located Brooks, the cougar was standing on top of the cyclist's body, Abbott said. Brooks had been "dragged a short distance to where the animal partially buried the body under a log," Myers said.
An officer fired a shot at the cougar but missed. However, the animal was spooked and ran off, Abbott said.
Soon after, dogs arrived and tracked down the cougar, which was in a tree 80 feet from Brooks' body, Abbott said. Fish and wildlife officials euthanized the animal, Myers said. A necropsy will be performed to try to determine what provoked the attack, including any disease.
Authorities said it was the second cougar attack death in Washington state in 100 years.
Cougars also are known as mountain lions, pumas and panthers.
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