Emergency crews in Ontario's Waterloo region are scouring the Nith River area of the community of New Hamburg for a missing boy who apparently left his parents' home without a jacket and headed toward the river.
Neighbours said the boy is five years old.
Rescue workers found footprints leading to a hole in the ice by the river's edge, with no footprints heading back.
Police have set up a command centre near the New Hamburg division of the Royal Canadian Legion to co-ordinate the search.