A hiker is believed to have been killed by at least one mountain lion in the US state of Colorado on Wednesday, according to wildlife officials.

If confirmed, it would be the first fatal attack there since 1999.

A group of hikers found the woman's body on a remote trail and spotted a lion nearby. After scaring off the predatory cat, they checked the body and could find no pulse, Colorado Parks and Wildlife (CPW) spokeswoman Kara Van Hoose said.

It was unclear whether one or multiple animals were involved in the attack, she added. Two mountain lions have been euthanised after an extensive search, and investigators are currently studying them for signs of human DNA.

The hikers had thrown rocks at the mountain lion to drive it away, Ms Van Hoose told a news conference. CPW officers responding to the scene shot the lion, which ran off. They then tracked it to euthanise it.

A second lion was found in the area and was also euthanised.

If neither lion appears to be the culprit, the search will resume for a possible attacker. Under CPW rules, wildlife that kills a human being must be euthanised for public safety reasons.

The woman's body showed signs of a mountain lion attack, according to Ms Van Hoose.

The local sheriff's office has notified her next of kin, and will later disclose her identity, Ms Van Hoose told the BBC. She is believed to have been hiking alone.

The Crosier Mountain Trail is north of Denver, near the Wyoming border, and close to Rocky Mountain National Park. It could be considered secluded, Ms Van Hoose said, adding that hikers often lose their phone signals there.

The Larimer County sheriff, police from the nearby city of Estes Park and volunteer firefighters have been assisting in the search.

A biologist conducting a deer survey by helicopter in the area helped look for the animal and transport personnel, according to CPW. Meanwhile, houndsmen brought dogs in to track scents, which Ms Van Hoose said was an often-effective way to locate mountain lions.

Mountain lion attacks - both fatal and not - are rare in the state, with CPW recording 28 total since 1990.

Mountain lions, also called pumas, cougars, catamounts or panthers, can be found throughout North America, but now are mostly in 15 western states, according to the Mountain Lion Foundation.

They are mostly solitary animals, who spend most of their time hunting, the foundation says. (BBC)