ST. JOHN'S, N.L. -- The president of a small Quebec airline says three people were killed when one of its planes crashed into a Labrador lake Monday.

Jean Tremblay, president of Air Saguenay, said the float plane was carrying four fishermen, two guides and the pilot. He said the condition of the four missing occupants is unknown.

Maj. Mark Gough of Maritime Forces Atlantic said military rescuers are searching for survivors at the crash site in Mistastin Lake, about 120 kilometres southwest of Nain, N.L.

Gough said a Hercules aircraft spotted the wreckage of the de Havilland DHC-2 Beaver float plane at 5 a.m. local time Tuesday.

He said the plane left a fishing lodge on Crossroads Lake, east of Schefferville, Que., Monday headed to a remote fishing camp on Mistastin Lake.

It failed to return to the lodge that evening, and people at the lodge were unable to reach the missing party by satellite phone.

Rescue officials said a helicopter was expected to arrive at the site Tuesday morning, and a second float plane had been dispatched to assist in search efforts.

The Canadian Transport Safety Board will investigate the crash.