A series of 'loud bangs' and 'explosions' were heard across Britain on Saturday night.
Social media users from Devon to Glasgow heard the mysterious sounds, which they believed were due to RAF jets' sonic booms.
But a Ministry of Defence spokesperson told the Daily Mail they did not know the cause of the sounds and have no records of jets being scrambled last night.
Members of the public reported the sounds between 9pm and 10pm and many compared them to the "massive explosion-like noise" which shook Kent last month when an RAF jet went supersonic to intercept a Russian-made cargo airliner and escort it to Stansted Airport.
According to the Daily Mirror, a Met police spokesperson said the only possible explanation was a fireworks display in Croydon.
Meanwhile Twitter user Virtual Astronomer explained to MailOnline: "Space debris such as old satellites and things can cause sonic booms heard over very large areas."
The noises were heard in London, Bedfordshire, Glasgow, Devon, West Sussex and Leicestershire.
Last month, CCTV footage captured the moment the Typhoon jet broke the sound barrier, producing a loud bang that was heard in Kent, South London and East Sussex.
The footage was taken by Tweetdeck founder Iain Dodsworth at his home in Crowborough, East Sussex.
He said he thought the noise was his "whole house collapsing", while others described it as sounding like "an explosion". One woman in Bromley said her double glazing shook with the force of it.
Did you hear any unusual noises on Saturday night? Leave a comment and tell us below.