A three-year-old boy is missing after the van he was riding in was swept into the Grand River.

A report of headlights bobbing up and down in the river brought emergency crews to a section of the river near Grand Valley, north of Belwood, early Wednesday morning.

The boy’s mother, who drove the vehicle down a road that had been closed to the public due to the river spilling its banks, was yelling for help when firefighters arrived.

She was pulled to safety and taken to hospital to be treated for hypothermia.

According to the OPP, the woman had pulled her son out of the van, but was pushed over by the fast-moving water and let go.

“(She) lost her grip … and he was swept away in the river,” said OPP Const. Paul Nancekivell.

The vehicle was located around 9:30 a.m., about four kilometres downstream of where the mother had been. It took crews a few hours to access it, search it and confirm that the boy was not inside.

A police helicopter, drone and underwater search team were brought in to help with efforts to locate the boy.

Police said their search efforts were focused not only on Grand Valley, but on areas where the boy may have been carried by the raging river.

The search was called off for the night around 6 p.m. Crews were expected to return to the area on Thursday.

With reporting by Nicole Lampa and files from CTVNews.ca