On Saturday, two mountain bikers were riding in the foothills of the Cascade Mountains in North Bend, Washington (near Seattle) when a cougar began stalking them and eventually attacked.

According to CNN, S.J. Brooks, 32, was killed by the mountain lion while his friend Isaac Sederbaum, 31, somehow survived and is currently hospitalized with severe injuries.

Authorities say the two men did everything right, but the cougar still attacked. Sederbaum even hit the cougar with his bike, which caused the cougar to retreat back into the woods.

But as the men were catching their breath, the cougar returned. The cougar was attacking Brooks while Sederbaum attempted to run away, causing the cougar to shift its attention and go after him. Brooks was bitten in the face, legs and neck, and Sederbaum’s injuries included bite and claw scratches to his head, neck and face.

The cougar eventually released Sederbaum and went back for Brooks, at which point Sederbaum rode two miles on his bike for cell phone reception to dial authorities. Officials later arrived at the scene to find the cougar on top of Brooks’ body, who was pronounced dead when authorities arrived.

Officials immediately shot at the cougar, which prompted it to climb a tree. They eventually euthanized the animal, which authorities called “emaciated,” as it weighed just 100 pounds (which is 40-80 pounds fewer than a typical three-to-four-year-old male cougar).

This has led officials to believe something was wrong with the animal, and a brain necropsy is being performed to determine what that might be.

“It’s an incredibly tragic story,” Capt. Alan Myers of the Washington Department of Fish & Wildlife told CNN. “It’s extremely unusual for a cougar to act this aggressively on humans.”

This is only the second fatal cougar attack in the state of Washington, the last being 94 years ago. And this is the first known fatality by a cougar in the U.S. since 2008.

Sederbaum underwent surgery on Sunday and remains in the hospital in satisfactory condition.

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