A sonic boom has been heard over London and Cambridge after two RAF jets were scrambled to intercept a private plane.
The aircraft was travelling from Germany and had lost communication with air traffic controllers.
It was diverted to Stansted Airport by the Typhoon jets, which took off from RAF Coningsby in Lincolnshire.
Several people reported hearing a "massively loud bang" in London, Cambridge and other areas in the South East as the fighter plane smashed through the sound barrier at nearly 750mph.
Posting on Twitter, Alistair Broomhead said: "Just heard a loud boom in E12, windows rattled, sounded like an explosion, anyone else in London hear anything? Know what’s going on?"
Javelin Sam, from Essex, tweeted a doorbell webcam video showing how loud the sonic boom was.
Another user, John Walsh, said: "Sonic boom just now over Cambridge! Blew my window off its casement stay and scared the bloomin’ life out of me and the several pigeons outside!"
Meanwhile, Londoner Jenny Hao said: "Has there been some sort of explosion in #Deptford? Just felt enormous bang whilst walking along the river in Greenwich and saw smoke."
Emma Boswell posted: "I was walking through Waltham Abbey when I heard it. Honestly thought a bomb went off but yeah it was a sonic boom in Cambridge!"
Others posted video of one of the jets flying over Stansted Airport and tracking data showing the aircraft’s earlier supersonic speed.
An RAF spokesperson said: "The RAF can confirm Quick Reaction Alert Typhoon aircraft were launched this afternoon from RAF Coningsby to intercept a civilian aircraft that had lost communications; subsequently, communications were re-established, the aircraft was intercepted and safely escorted to Stansted.
"The Typhoon aircraft were authorised to transit at supersonic speed for operational reasons."
The jets are often deployed to escort aircraft that lose contact with air traffic control or don’t respond to communications.
The Typhoon can go from brakes off to Mach 1.5 (1150 mph/1852 kmh) in two and a half minutes, according to the RAF.
Its top speed is Mach 1.8 (1381 mph/2222 kmh).
The speed of sound in air varies according to temperature – according to today’s temperature in Cambridge it would have been around 748mph (1204kmh).
The jet – based at Coningsby and RAF Lossiemouth – can carry air to air missiles and is also compatible GPS and laser-guided Paveway bombs.
© Sky News 2021