A search operation is under way after a two-year-old boy fell into the River Soar in Leicester on Sunday evening.
Emergency services attended the scene in Aylestone Meadows, close to Marsden Lane, just after 5pm.
The child was with his family when the incident occurred but was not located “despite the best efforts of those at the scene”, Leicestershire Police said.
A man was taken to hospital “as a precautionary measure”.
Additional specialist teams will join the search operation on Monday morning.
Police said they have received several offers of help with the search but warned the public not to attend the scene due to rising water levels and safety risks.
In a statement, Leicestershire Police said: “The child’s family are being supported by specialist officers and our thoughts are with them at this extremely difficult time.
“If anyone has any information or comes across anything that may assist officers, they are asked to contact us immediately.”