RCMP Const. Michael Potvin is missing after his boat capsized on the Stewart River near Mayo on Tuesday evening.
Potvin and another RCMP member were travelling downstream toward their docking point in an aluminum RCMP boat when the craft started taking on water and flipped. The capsizing happened just before 8 p.m.
One member stayed with the boat, while Potvin attempted to swim to shore.
Witnesses who saw the incident paddled out in the river to rescue the member who stayed with the overturned boat.
But Potvin could not be found.
The 26-year-old was not wearing a personal floatation device.
Approximately five RCMP members, as well as volunteers, searched the river and shoreline until after midnight. The search began again at first light Wednesday morning.
Potvin was one of three officers based in Mayo. He had one year of service.