A 'loud bang' heard across Derbyshire was a result of a Royal Air Force jet passing over the area which caused a sonic boom.
Residents took to social media to say their homes were 'shaking' and car alarms were going off.
Derbyshire police said it was particularly heard in the Ilkeston and Derby area just before 10am.
Derbyshire police tweeted: "If you heard a loud bang over Derbyshire today, this was as a result of a Royal Air Force jet passing over that caused a sonic boom."
"And Derbyshire Fire and Rescue Service tweeted: Loud bangs that could be heard across Derby and and parts of Derbyshire are being attributed to a sonic boom caused by a low flying aircraft."