Officers from the Metropolitan Police attended, along with paramedics from the London Ambulance Service and the RNLI.
Upon arrival, emergency responders discovered a body in the water.
Photos shared on social media also show a fire engine in attendance, as well as several police vehicles and a police tent being set up.
One person tweeted: “Saw the RNLI rushing to the scene with sirens (unusual) so must have been a water related incident. Hope everyone is well.”
The man is yet to be identified by police.
In a statement a Met spokesperson said: “Police were called at 16:18hrs on Thursday, 10 June to a report of a body in the Thames around York House Gardens in Richmond.
“Officers attended along with colleagues from the London Ambulance Service and the RNLI. A male was later recovered from the water. Enquiries continue.”