Search for toddler in Vic creek called off

Police are urging parents to be vigilant around fast-flowing water as a toddler remains missing after falling into a swollen Victorian creek.

Authorities will resume looking for the three-year-old boy on Thursday morning.

The full-scale search was called off when darkness fell on Wednesday, about four hours after a witness reported the child had fallen into Dandenong Creek.

Superintendent David Clayton said it was a grim situation, especially for the child's parents.

"You couldn't imagine the pain the parents are experiencing at the moment with their child missing, presumably in the creek," he told reporters at the scene.

"It is grim.

"Obviously the child has been in the water for a long period of time, we believe.

"So it's very concerning for the parents and obviously they're very distraught."

The incident occurred one day after heavy rain lashed the state.

The boy had reportedly been playing with his family in a nearby park beforehand.

Supt Clayton urged parents to be vigilant around fast-flowing water.

"Our message would be to parents, to be very aware that there is fast-flowing water and they need to be vigilant with their children around obviously fast-flowing water," he said.

A helicopter circled in the afternoon and a number of emergency service crews searched the area, but the child had not been sighted.

"The search is quite extensive. We've got a large number of police personnel here and SES assisting with a line search," Supt Clayton said.

Dandenong Creek is an urban catchment in outer Melbourne.