Did you hear the sonic boom today?
- Credit: Gregg Brown
A 'sonic boom' has been heard by millions of people across Essex, Cambridgeshire, Hertfordshire and London.
Many people have reported hearing the loud bang, which is said to have been caused by an RAF fighter jet breaking the sound barrier.
Cambridge City Council tweeted: "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!"
People took to social media to share their reactions to the huge bang.
Essex Police has been contacted for comment.