The death toll from a small plane crash in Canada's Northwest Territories was six, authorities said on Wednesday. The plane was carrying employees from the Rio Tinto mining company.

The Northwest Territories coroner's office said that four passengers and two crew members from Northwestern Air Lease were killed in Tuesday's crash, while a lone survivor was taken to a hospital and later airlifted to Yellowknife.

The plane took off from the airport in Fort Smith, and then crashed near the banks of the Slave River.

Rio Tinto said that a number of its staff were on the plane, which was headed to its Diavik Diamond Mine, about 300 kilometres northeast of Yellowknife, Northwest Territories.

“I would like to extend our deepest sympathy to the families, friends, and loved ones of those who have been affected by this tragedy. As a company we are absolutely devastated by this news and offering our full support to our people and the community who are grieving today,” Rio Tinto chief executive Jakob Stausholm said in a earlier statement.

“We are working closely with authorities and will help in any way we can with their efforts to find out exactly what has happened.”

The town council said in a statement that those who died are treasured members of the community and their loss touches everyone. The town said that people are welcome to go to the community recreation centre today for snacks, drinks and friendly faces.

The town of Fort Smith is about 2,100 kilometres northeast of Vancouver, British Columbia, near the border between Alberta and the Northwest Territories.

Canada's transportation safety board is sending investigators to the scene. The Canadian military responded when the plane lost contact shortly after taking off near Fort Smith.