04/26/2017 09:23 EDT | Updated 04/26/2017 09:40 EDT

Three helicopters, 70 people search for four missing hunters in northern Alberta

FORT CHIPEWYAN, Alta. — A search for four hunters missing in the remote northeastern Alberta wilderness is ramping up with three helicopters and more than 70 people.

RCMP say the hunters left Fort Chipewyan on Sunday night in a boat on the Rocher River.

The boat was found in the river that flows through Wood Buffalo National Park.

Mounties, Parks Canada staff, a search-and-rescue team from Fort McMurray and civilian volunteers — including people in 30 boats — are looking for the four men.

The searchers include people from the Mikisew Cree and the Athabasca Chipewyan First Nations.

RCMP Cpl. Ronald Bumbry says searchers are looking along the river and its tributaries in the heavily wooded area.

Bumbry says the missing hunters all have experience in the outdoors.

"There is always a concern for anyone who is out in the wilderness for long periods of time," Bumbry said Wednesday. 

"We continue to search for these individuals and we won't stop until they are found."

Temperatures in the search area have been just above freezing and weather has not been hampering the search effort.