A search operation for a man who fell into the Humber River Wednesday afternoon has been suspended but it is expected to resume Thursday, fire officials say.

The search was put on hold due to concerns about emergency personnel working in the dark, Toronto Fire platoon chief Jim Slobodian told CP24.

“We don’t want to put our guys in peril, so we’re shutting down operations until (Thursday) morning,” he said.

Emergency crews were notified around 5:30 p.m. that a man had entered the water and was swept away. The man is believed to be in his 20s.

Crews say they believe the man had gone near the river after his dog, and may have been carried downstream from Lion’s Park located near Lawrence Avenue and Weston Road in the city’s northwest end.

Police, fire and marine units scoured the river along the shoreline in an attempt to locate and pull the man from the fast-moving waters. Rescue personnel were also stationed at bridges and dams along the river.

Toronto Fire spokesperson Stephan Powell told CP24 there have been some reported sightings of the man in the water, but rescue crews had yet to spot him Wednesday night.

Emergency personnel are concerned for the man’s safety, as the waters are quite cold.

“The water temperature is going to rob anybody of their strength,” Powell said. “Hypothermia will set in pretty quickly.”

Powell said earlier Wednesday fast-moving, muddy waters were hampering rescue efforts.

Given the current conditions, he also advised people to stay away from river banks.

“The ground is soft, it’s waterlogged, it could easily be dislodged by you standing near the bank and you could fall in and before you know it, you could be swept away.”

Heavy overnight rain caused the river to swell Wednesday.