Wardens in Banff National Park are confident they shot a cougar that killed a female skier Tuesday. But they say they are at a loss to explain the attack.

The 30-year-old woman was cross-country skiing along the Cascade fire road near Lake Minnewanka when she was attacked. Another cross-country skier reported the incident after seeing a cougar standing over the woman's body, says Chief Warden Ian Syme.

"When we got to the scene, the cougar was still there, so we shot the cat," he says. "We're trying to determine what caused the attack. The preliminary indication is that it was a stalk." But Syme says it's not known whether the woman knew she was being stalked.

It was the third cougar sighting in the Banff area that day. But officials are sure the male cat which pulled down the skier is not the same one that stalked another woman who was walking her dog near the Banff Springs Hotel. A neighbour opened his gate allowing them to escape unharmed.

A few hours earlier, John Peck woke up to see his Alaskan husky being attacked. He managed to scare off the cat, but his dog ran away. The dog has since returned home, and except for a few bite marks, it appears to be in good shape, says Peck.

Syme says there are only half a dozen or so cougars in the Banff area, and such behavior is rare. "They are solitary. They are rarely seen and to have three incidents, including one very tragic one, is unusual," he says. "As far as a fatality goes, this was a first for Banff, a first for Alberta."

A wildlife biologist in Calgary says there have been only 98 attacks by cougars in the past 110 years. Of those, 18 were fatal, says Ian Ross, who has spent years studying cougars in the Rocky Mountains.

A carnivore specialist from British Columbia suggests increased sightings and attacks in Canada and the U.S. have a lot to do with the availability of food. There are lots of elk in the Banff area, says Sean Sharpe, head of the Wildlife section in B.C.'s Skeena Region.

Be "extra aware of what's going on around you," he says. "Keep your eyes open for tracks. If you should encounter a big cat like a cougar, show it that you are not something good to eat. Make yourself bigger. Put your hands over your head and just move away slowly."

All popular cross-country ski trails in the Banff area have been closed. Wardens spent Tuesday night going door to door advising residents not to venture out alone.

But some say encounters with wildlife are what living in a national park is all about. However, one woman says she will not go into the back country alone anymore and never after dark.

For more information, click here to listen to Ian Syme, Chief Park Warden with Banff National Park