Technicians and emergency personnel help transfer a survivor of a crash in the Labrador wilderness Monday. (Mike Power/ CBC)

Four people injured after a small plane crash-landed in western Labrador have been flown to hospitals in St. John's and Quebec City for further treatment.

The De Havilland Beaver was carrying four American anglers, two fishing guides and a pilot when it crashed minutes after taking off from a fishing lodge in the isolated Labrador bush, not far from the Quebec boundary.

All seven survived the crash, but the Royal Newfoundland Constabulary said two people were critically injured. Two others required medical treatment for less serious injuries, which were not described in detail.

Kevin Barry, one of the owners of the fishing lodge, said Monday night he was relieved the outcome of the crash was not tragic, and credited the action of military rescuers who flew to the scene aboard a Hercules aircraft and two helicopters.

"Within two hours, we had a team there, and parachuters out and people being attended to, so it's really grateful," said Barry, who had leased the Air Saguenay aircraft.

"Two are going to Quebec City, two are going to St. John's [and] there's no life-threatening injuries."

One of the outfitters is Barry's uncle, who was able to walk away from the crash.

It's not yet known what caused an apparent sudden loss of power on the plane.

The Transportation Safety Board of Canada is launching an investigation.

Search-and-rescue officials dispatched a Hercules aircraft from Greenwood, N.S., a Griffon helicopter from Happy Valley-Goose Bay and a Cormorant helicopter from Gander, soon after receiving a distress call on Monday morning.

Master Cpl. Bryce Culver, a search-and-rescue technician with Gander Rescue Squadron, said he quickly realized how grateful the survivors were after he arrived on the scene.

"When they were going down, [a passenger] felt this might be the end … and he just was overwhelmed that there were these three large units that were all working together to help everybody out," Culver said.

Apart from the four individuals receiving treatment in Quebec City and St. John's, the three other passengers were treated and released Monday from hospital in Labrador City.