The Duke of Cambridge was reportedly called to pilot an Air Ambulance helicopter to a country park to save a drowning boy.
The emergency services were alerted and 34-year-old William, along with the rest of the crew, searched for the teen for an hour.
Robbie Lea, as he was named locally, was at Lee Valley Park in Cheshunt, Hertfordshire, last night at 7pm.
The East Anglian Air Ambulance crew, and The Duke of Cambridge were called to the scene, as well as other emergency services.
Shortly after William’s team got there, the police told them that the boy’s body had been found and he was pronounced dead at the scene.
An unnamed eye-witness told The Telegraph: “We knew something was up when a helicopter was flying extremely low just over the Lee Valley Park.
“We could see it was landing so ran over to see what was going on. Little did we expect to see Prince William himself flying the helicopter.
“It was a very surreal moment when he left the helicopter to help with the search and rescue, he had no visible guards or protection.”
“He arrived in an East Anglia Air Ambulance with one other co-pilot.”
Hertfordshire police have said they aren’t treating the lad’s death as suspicious.
A police spokesman said: “A search led by the fire service was carried out.
“The boy was recovered from the water, but sadly he was pronounced dead at the scene.
“There are no suspicious circumstances and a file will be prepared for the Hertfordshire coroner.”
On Tuesday, Prince William issued a statement on Twitter after the the Manchester suicide bombing at the MEN arena on Monday night.
He said he was “shocked and saddened by the tragedy” and thanked everybody who helped display “strength” and “decency” during that difficult time.
On Thursday, his grandmother The Queen attended the Royal Manchester Children’s Hospital to talk to the staff and the victims that have been injured in the blast.