A bear expert who's a family friend of one of two people killed by a grizzly bear in Banff National Park says the couple was experienced in the outdoors and could have been in the wrong place at the wrong time.

Kim Titchener, who has a company called Bear Safety and More, says both the couple and their dog died in the backcountry on the weekend.

Parks Canada has said in a statement that its dispatchers received an alert around 8 p.m. Friday from an inReach GPS device about a bear attack west of Ya Ha Tinda Ranch, which is about 200 kilometres northwest of Calgary.

The federal agency immediately sent its Wildlife Human Attack Response Team to the area by ground because it could not use a helicopter due to weather conditions in the mountains.

It says the team arrived around 1 a.m. Saturday and found two people dead.

Parks Canada says the team encountered a grizzly bear displaying aggressive behaviour and killed the bear to further protect the public.

The Red Deer and Panther valleys from the Snow Creek summit east to the national park boundary, and north to Shale Pass is closed as a safety precaution until further notice.

Banff National Park, which is Canada's first and busiest national park, is home to both grizzly and black bears.