Emergency services are searching for a man after he got into difficulty in the Thames River near Hampton Court bridge.
The London Ambulance Service was called to the scene just before 4.15pm on Sunday.
A spokesperson told the Standard staff are still looking for the man.
Witnesses have reported seeing a number of emergency services at the river bank, including police and helicopters and people searching in boats.
The incident comes after a teenage boy died after going into the sea at Skegness.
Lincolnshire Police said emergency services were called to the scene at around 6.15pm on Saturday after receiving a report that a child under 16 was “in the water”.
Meanwhile a body was found in a Doncaster lake after reports that a man in his 20s had got into difficulty.