Two friends riding their bikes in a mountainous, wooded area of Washington State on Saturday morning were attacked by a cougar, which killed one of them in the state’s first such fatality in more than 90 years, officials said.

The authorities said the two cyclists saw the cougar, a 100-pound male, in pursuit and one of them screamed. They stopped, got off their bikes and made noise to ward it off as people in such situations are advised to do, the authorities said.

At first, it appeared to work. The cougar fled.

But as they were about to pedal away, the cougar returned, Sgt. Ryan Abbott of the King County Sheriff’s Office said. It jumped on Isaac M. Sederbaum, putting its mouth around his head and shaking him. It released him and chased after the other cyclist, who had started to run. The authorities identified that cyclist as Sonja J. Brooks.

As Sederbaum, who had been bloodied but survived, rode away from the scene, he could see the cougar dragging Brooks into the woods, Sergeant Abbott said. Sederbaum later told the authorities that he had to travel about two miles before getting a cellphone signal and calling 911.