Once police were notified on Thursday, four firefighters and a police officer began scouring the St. Charles River in Valleyfield, south of Montreal.
When their boat hit the pillar of a bridge, all five tumbled out and into the frigid water.
A police officer on shore who was keeping watch called in other firefighters. With the help of some rescue lines, they pulled the five from the water.
Four of the five were sent to hospital, at least one of them with hypothermia. But, according to provincial police Sgt. Ingrid Asselin, all were released from hospital within several hours and are doing fine.
The search for the possible body continues — this time by helicopter.