Details continue to emerge about the four Canadians who were among at least 20 trekkers killed in an avalanche and blizzard in Nepal Tuesday night.

The Quebec travel agency Terra Ultima confirmed Wednesday that three Quebec women on one of its high-altitude tours were missing after the avalanche.

Terra Ultima said one of those missing was a 55-year-old female employee of the company, who was in Nepal to lead the hiking trip. The other two were aged 33 and 59. Terra Ultima says one woman was from Quebec City and the other two were from Montreal. They left Quebec on Oct. 3 and were due to return Oct. 24.

Terra Ultima employees learned of the avalanche early Wednesday and worked through the morning to contact the women's families, they said.

Two Nepal-based hiking companies responsible for treks in the region have confirmed the deaths to the Associated Press. Panorama Himalaya has confirmed the deaths of the three Canadians, while Nepal Hidden Treks has confirmed the death of a fourth Canadian, a woman.

The fourth Canadian victim’s identity and home province have yet to be determined.

Two Ottawa-area women, Virginia Schwartz and Jane Van Criekingen, were initially believed to be among the hikers caught up in the avalanche. But it turned out that they were “totally oblivious” to the catastrophe as they trekked in the danger zone, Schwartz’s brother told Canada AM Thursday.

Family members have yet to hear from Rose Maninang and Marc Voyer of Toronto, who are currently unaccounted for. The couple has been travelling in the region since March and had registered to hike in the area where the avalanche occurred.

“What I’m hoping for, based on the fact that we haven’t heard contact is that they’re oblivious to the drama that’s completely around them,” Voyer’s syster, Nadia Chychrun, told CTV Toronto Thursday.

“I can imagine it’s complete chaos at the moment.”

Chychrun said her family is trying not to draw any conclusions until they get more information from Nepal.

Representatives from the Trekking Agencies' Association of Nepal said three other Canadian trekkers have been rescued.

Canadian officials continue to look into the deaths and are in contact with local authorities in Nepal, a spokesperson for Foreign Affairs and International Trade Canada told CTV News.

The spokesperson would not release details about the victims, “to protect the privacy of affected individuals.”

Prime Minister Stephen Harper tweeted his condolences to the families of the hikers on Wednesday.

Rescuers say it could take days to recover the bodies of the dead Canadians.

With files from CTV Toronto's Ashley Rowe, the Associated Press and CTV Montreal