S.J. Brooks and Isaac Sederbaum did what they were supposed to do, authorities say. They made loud noises to scare the cougar away. One of them even struck the animal with a bicycle.

But none of it worked. The big cat that had been following the two friends as they were mountain biking in rural Washington state pounced, lunging at Sederbaum’s head and killing Brooks, whom the animal mauled in its den.

The attacks Saturday morning — the first fatal one in the state in nearly a century — was uncharacteristic of cougars, which are normally solitary animals that run off when confronted by humans, said Capt. Alan Myers of the Washington Department of Fish and Wildlife. The adult male cougar stalked the cyclists, and instead of running away after the victims tried to scare it off, the animal returned and attacked them.

“Humans are not on the menu for cougars normally,” Myers told The Washington Post. “For it to attack two human beings in the manner that it did was incredibly abnormal. … They do everything they can to avoid human contact.”

Cougars also usually hunt at night. The attack on the bikers happened in broad daylight, just after 11 a.m. Saturday.

“Something was wrong with this cougar,” Sgt. Ryan Abbott, spokesman for the King County Sheriff’s Office, told the Associated Press.

Myers said a preliminary examination of the animal, which has been euthanized, revealed that the 3- to 4-year-old, 100-pound male cougar was slightly emaciated. Adult male cougars usually weigh 140 to 180 pounds.

It’s unknown what would cause cougars to behave violently against humans. The big cat’s carcass was taken Sunday to Washington State University in Pullman, where a veterinarian will conduct a necropsy to determine whether it had a disease or injury that might have caused it to act so abnormally and to verify through DNA and tissue sampling that it was the cougar responsible for the attack, Myers said.

Brooks, 32, and Sederbaum, 31, were mountain biking on a dirt road near North Bend, a foothills town 30 miles from Seattle when they realized that a cougar was chasing them. They managed to drive the cat away, at least at first, by making loud noises — something that authorities recommend people do during such encounters. The cougar ran toward the bushes after one of the victims swung a bicycle at it, Abbott said.

But just as the two were about to leave, the cougar jumped back and pounced on Sederbaum, holding his head with its jaw and shaking him from side to side. At one point, Brooks got off the bike and ran away, catching the attention of the big cat, whose instinct was to chase. Injured and bloodied, Sederbaum hopped on his bike and rode away. He looked back and saw the cougar dragging his friend into the woods, Abbott said.

Sederbaum rode about two miles to find cell reception and called 911. He suffered deep cuts and tears around his head and throughout his body, Myers said. His cheek was torn open. He was taken Harborview Medical Center in Seattle, where his condition was later upgraded to satisfactory, according to media reports.

First responders from the fire and sheriff’s departments found Brooks in the cougar’s den, with the cougar on top of him, Abbott said. One of the deputies fired a shot, scaring the animal away. Officers with the Washington Department of Fish and Wildlife used hounds to track the cougar, which they found behind a tree 80 feet away, Abbott said.

Brooks was brutally mauled, Myers said.

Friends said Brooks was an avid cyclist who moved from Boston to Seattle not long ago and immediately fell in love with the outdoors. Tyler Gillies said Brooks had been leading cycling trips in the past year to the remote area where the attack occurred.

“I have so many friends that ride out there all the time,” Gillies told KIRO. “I do the same thing myself. It is a perfectly safe and wonderful thing to do. And S.J. was in the wrong place at the wrong time, and I’m just crushed.”

Tom Fucoloro, a writer for Seattle Bike Blog, said Brooks had created a local bike community in which women, transgender people and others can feel welcome.

“A lot of women, especially women of color, would go into bike shops and have a bad experience,” Brooks told Fucoloro in an article published last year. “And that bad experience means even though someone might bike to get around, a bad bike shop experience might dissuade them from learning more.”

Myers said the mountainous, wooded area where Brooks and Sederbaum were attacked is home to many cougars. Statewide, there are about 2,000 cougars living in the wild. But attacks are extremely rare.

Before Saturday, 16 cougar attacks, one of which was fatal, had been reported in Washington state during the past century. The first known fatal attack occurred in the 1920s, when a boy named Jimmy Fehlhaber was devoured by a male cougar.

About 120 attacks, 25 of which were fatal, have been reported in the United States and Canada in the past 100 years.

However, attacks involving cougars, also known as mountain lions, have been increasingly common in the past 20 years. In Washington state, for example, seven of all reported attacks occurred during the 1990s. Myers said one possible reason for the uptick is humans’ encroachment of wildlife.

“Human population has moved to rural areas and started to develop and became in contact with wildlife more often,” Myers said. “That might be one of the reasons. In this time frame, people have certainly been pushing into wilder and wilder areas.”

If you encounter a cougar, don’t run — because the animal’s instinct is to chase. Instead, authorities advise people to never take their eyes off the animal and to try to appear larger and more intimidating. Shout, wave your arms and throw rocks, anything to let the animal know you are a threat and not prey.

“If the cougar attacks, fight back aggressively and try to stay on your feet,” according to the Washington Department of Fish and Wildlife. “Cougars have been driven away by people who fought back.”

Read more:

Yes, that’s a monkey grinding on top of a deer

Florida teacher accused of drowning raccoons in class resigns as state agencies investigate

A Bengal tiger was shot dead after it wandered into a Georgia neighborhood and attacked a dog