Police divers have pulled a body out of the River Thames after reports a swimmer was calling for help after getting into difficulty by Hampton Court Bridge.
The man, in his early 20s, was found by police divers in Hampton Court, south-west London about 10.30pm on Sunday.
Three police forces, firefighters, a helicopter and the RNLI kicked off the frantic search after being alerted to a person in the water about 4.15pm that day.
The victim’s family has been informed of the discovery.
Eyewitness Max Taylor was paddle-boarding at Hampton Court and told Sky News he had spoken to a couple who had seen the man in the water.
He said: “They told me a young male in his mid-late teens was swimming in the river near Hampton Court bridge.
“He called for help and was in waist deep water. They said they thought he was joking as he wasn’t in deep water - seconds later he had disappeared.”
Leader of Richmond council Gareth Roberts, tweeted: “Absolutely heartbreaking that almost a month to the day after Brian Sasu lost his life at Taggs Island, there has been another tragedy in the river, just a little further along at Hampton Court.
“Please, if you have young family or work with young people warn them of the danger.”
Superintendent Richard Smith, Acting Commander for the South West, said: “Our thoughts go out to the young man who has lost his life. Our officers worked incredibly hard with partner agencies but despite a rapid response he could not be rescued.
“We recently saw another tragic incident in which a young boy died after entering the Thames at Tagg’s Island. I must again sadly reiterate the dangers the water poses.
“It may look appealing but the danger and risk of loss of life is incredibly real. Please do not enter the water at any point. The consequences are enormous and we do not want to see any more families having to suffer such terrible news.”