The search for a missing 3-year-old boy in the Grand River, southwest of Grand Valley, has been called off for the night.

Rescue teams have been canvassing the area for any sign of the child since early Wednesday morning.

OPP say the child was in a minivan that ignored a road closure sign near 10th Line just before 1 a.m., and drove into some water before becoming fully submerged in the river. The fast-moving current carried the van four kilometres downstream, and remains lodged in the riverbed near the Highway 109 bridge.

Constable Paul Nancekivell tells CityNews the female driver escaped with the child in her arms, but he slipped from her grip and was swept into the river.

Centre Wellington Fire and Rescue crews, along with an OPP emergency response team and an OPP dive team are canvassing the area for any sign of the child.

BREAKING: OPP confirm they are looking for a 3-year-old boy who slipped from his mother’s arms after the van became submerged @CityNews pic.twitter.com/G7SEf2eocl — Amanda Ferguson (@CityNewsAmanda) February 21, 2018

“You never know, the child could be caught in branches or things like that on the edge of the river,” Nancekivell says. “We’ve had two centimetres of rain over the last 48 hours.”

The woman is being treated in hospital for hypothermia.

The boy’s father is on the scene to assist in the search for his son, but has not spoken with reporters.

Centre Wellington Fire Chief Brad Patton maintains this is a complex and risky operation because of the strong current.