A vicious cougar attack Saturday left one person dead and another seriously injured, Washington state authorities said.

The victims, Isaac Sederbaum, 31, and S.J. Brooks, 32, were biking on a trail 30 miles east of Seattle around 11 a.m. when they realized the animal was chasing them.

According to Sgt. Ryan Abbott, a spokesman for the King County Sheriff’s Office, they drove the cougar away by making loud noises, a common recommendation from authorities in such encounters.

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One of the bikes also hit the big cat with his bike. The cougar disappeared, but not for long.

As the pair geared up to ride away, the animal pounced on Sederbaum.

“The first victim told us that the actual cougar’s mouth was around his head. The cougar was trying to shake the victim from side to side,” Abbott said.

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Brooks ran, and the cougar dropped his friend to chase him next, killing him and dragging him back to his den.

Sederbaum suffered deep cuts throughout his body and is recovering at Harborview Medical Center, according to KIRO 7 Seattle.

“They did everything they were supposed to do,” Abbott said. “But something was wrong with this cougar.”

First responders found Brooks deep in the woods less than three miles away from the scene with the animal on top of him. Abbott told the Washington Post that one of the deputies shot the cougar and missed, but the gunshot scared the animal away.

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Officials with the Washington Department of Fish and Wildlife, who tracked down the animal hours later, said on Sunday that the animal was underweight at about 100 pounds. Typically, 3-year-old male cougars in the area weigh about 140 to 180 pounds.

The animal’s carcass was sent to a lab at Washington State University for a necropsy of the rare attack.

“This is not a normal way that a cougar acts,” Abbott said. “Most of the time, they’re very afraid. … Most of the time, they run off quickly.”

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According to the Washington Department of Fish and Wildlife, there had only been 16 cougar attacks previously reported in the state in the past century, only one of which was fatal.

In the United States and Canada, there have been about 120 in the past century, 25 of which were fatal.

"However, attacks involving cougars, also known as mountain lions, have been increasingly common in the past 20 years as humans encroach on wildlife habitats," the Washington Post reported.

Learn more about what to do if you encounter a cougar at wdfw.wa.gov.