A « sonic boom » has been heard by residents in Cambridge and London.
The large bang, thought to have come from an RAF fighter jet, was heard at around 1.19pm today.
People in Hertfordshire and Essex also reported hearing the bang.
« If you heard a massively loud bang over #Cambridge in the last few minutes, don’t panic – apparently it was the sonic boom from a fighter plane breaking the sound barrier! » Cambridge City Council tweeted.
It is understood an RAF plane was scrambled to escort an unresponsive jet to Stansted airport.
Social media users took to Twitter to describe what they heard, with some saying their houses vibrated due to the force of the boom.
One wrote: « I thought my next door neighbours were gonna come flying through the wall. So scary! #sonicboom ».
A second said: « Sounds like the whole Romford area felt it, whole house shook and you could feel it in the ground ».