"Loud explosions" heard across the east of England were caused by a sonic boom when a jet broke the sound barrier.
The noise, at 11:30 BST, caused shaking and smashed windows and prompted calls to police in Cambridgeshire, Essex and Hertfordshire.
The Ministry of Defence said a Typhoon jet from RAF Coningsby in Lincolnshire was launched when communication was lost with a Heathrow-bound plane.
It is understood the plane, travelling from the USA, landed without incident.
Air traffic controllers had become concerned but communication was re-established with the passenger airliner and there were no problems on board.
'Whole house shook'
Speaking of Sunday's sonic boom, Insp Matt Snow of Cambridgeshire Police said: "We've had reports of windows being smashed.
"One man who rang us from St Ives thought something had hit his roof because the whole house shook.
"It was so loud another person thought his neighbour's house had blown up.
"People have said they'd never heard anything so loud in their lives.
"Even people driving on the A14 have been calling us."
Elaine Mason, of Great Gransden, Cambridgeshire, told the BBC: "I had just got on my horse and was walking around the arena, when I heard a thunderous bang.
"I couldn't believe it was thunder, it was about 10 times louder than that.
"I thought it might have been an explosion. She [the horse] reacted immediately."
Her husband, Tim, who was gardening nearby, said he thought the "almighty bang" could have been a crash.
Jets from RAF Coningsby were scrambled last month to escort a passenger plane over the UK.
The airliner from Pakistan, heading to Manchester, was diverted to Stansted and two men on board arrested by Essex Police.
The BBC understands the incident was not terror-related.