This morning Londoners were woken up by a loud bang caused by RAF fighter jets, police have said.
The sonic boom was heard across parts of North London, Hertfordshire and Bedfordshire.
People tweeted that a loud "explosion" caused windows to shake and police sirens had woken them up at about 4.20am today.
Now social media users have shared footage of the moment they heard the loud bang.
A video recorded at 4.17am shows the exterior of a property when the sudden sound echoes.
Another clip, filmed from inside the property, shows a sleeping cat being woken up by the sudden noise.
Two Royal Air Force Typhoons were scrambled from Coningsby in Lincolnshire after an aircraft lost communication in UK airspace, the Ministry of Defence said.
“The aircraft was intercepted and its communications were subsequently re-established. The Typhoons are returning to their base.”
London’s Metropolitan Police said: “The loud bang heard throughout north London and surrounding areas was the result of a sonic boom from RAF planes. There is no cause for concern.”
A sonic boom is a loud sound which resembles an explosion.
It is produced by an aircraft or another object flying at a speed equal to or exceeding the speed of sound, according to Encyclopedia Britannica .
In 2017, two RAF Top Guns were scrambled to "intercept" Theresa May's plane in a mock Typhoon mission to help pilots train to protect British airspace.
The Eurofighter Typhoons roared away from their base at RAF Coningsby, Lincs, before pilots spotted the PM's plane at 17,000ft above the North Sea.
Mrs May said later: “I'm delighted to have the opportunity today to see our brave pilots and crew in action refuelling in the air to prepare to fight Daesh (ISIS) over Syria and Iraq.
“Witnessing the unique skill of the RAF at first hand is an absolute privilege and once again demonstrates that the British Armed Forces are the finest in the world.
“The work they do is admirable and impressive and I want to take this opportunity to thank them for everything they do.”
