Police Const. Eric Hofley says police responded to a call Saturday morning when someone on the river reported seeing a body.
Police have been searching for a 32-year-old mother of two children who were found dead in their home Wednesday.
Officers have been concentrating their search for Lisa Gibson on the family's riverside neighbourhood.
Emergency personnel were searching the Assiniboine River on Friday.
Police say the unidentified body was found downstream of where the Assiniboine empties into the Red River.
Although there are reports Gibson's children died in the bathtub, police say the cause of death has not yet been determined.