Emergency services across swaths of England were inundated with calls from worried residents amid reports of a mysterious "loud bang" which turned out to be a sonic boom from two RAF Typhoon jets.
Concerned locals across the Home Counties, Cotswolds, Wiltshire, Somerset and parts of the Midlands reported hearing the deafening noise shortly after 6pm on Thursday amid fears of a large explosion.
But rather than anything sinister, it was a sonic boom caused by a pair of Royal Air Force Typhoon jets breaking the sound barrier, the Ministry of Defence said.
The Quick Reaction Alert (QRA) crews were scrambled after a civilian helicopter emitted an emergency signal in the Oxford area.
MoD sources said the "idiot" pilot, who has not been identified, had used a wrong frequency to emit the emergency signal that usually indicates an aircraft has either been hijacked or had "gone rogue".
Fearing that a serious incident was unfolding, MoD officials gave the jets the green light to go "supersonic, which resulted in the sonic boom".
The jets, based at RAF Conningsby in Lincolnshire, were already on route by the time the pilot realised his mistake and switched to the correct one.
An aviation source close to the incident, said: "It was caused by a helicopter transmitting a hijack code which triggered the launch of the two Typhoons.
"Supersonic flight was authorised by London Military Air Traffic Control which is only allowed in exceptional circumstances over land." The MoD response was standard procedure after receiving such a signal, officials said.
But such was the extent of the noise that homes started to shake across Coventry, Rugby and Leamington as hundreds of residents rang police and emergency services.
One video posted to Twitter, believed to be a crack of thunder by the person behind the camera lens in Northamptonshire, was later reported as the sonic boom by Channel 4 News.
Meanwhile, residents around Bath and Swindon reported seeing the fighter jets performing manoeuvres in the skies overhead.
Chris Wilford, 38, a Bath resident, told The Daily Telegraph that the jets kept circling the helicopter and "looked very close" to the aircraft, which he thought was a police helicopter at first.
"(It) slowed down and seemed to sharply pull round at one point (and) looked very near the helicopter from where I was watching," the council manager said.
"Around the helicopter, they pulled so sharp that the jets nose pulled almost verticle and you could see it was a triangle shaped Jet.
"It was very noisy, at first, because planes on their way to Bristol airport regularly fly over, I thought it must have been one of those, it was very low. I saw the helicopter first then the Jet arrived."
Alison Howell, 33, a resident from Leamington Spa, Warks, said she thought there had been a huge car crash outside of her house.
"The noise was just deafening, it sounded like a massive car accident right outside my front door," she said.
"It was pretty terrifying to be fair. I nearly jumped out of my skin.
"The windows shook and I thought they were going to break. I've never heard anything like it in my life."
Mandy Leech, 44, from Coventry, added: "If it was just somebody accidentally pressing a button in his helicopter I won't be very happy because it woke my baby up and scared the life out of me."
Inspector Phil Rogers, of Thames Valley Police, said his force had been "inundated with calls".
"We were concerned to start with but there were no reports of any explosions, damage or casualties," he said.
"The calls we got were widespread."
A spokesman for West Midlands Police added: "The cause of the noise is not known at this stage however we can state that the 'incident' does not require any direct police attendance."
On Thursday night an MoD spokesman said: "We can confirm that a small civilian aircraft was transmitting inadvertently on an emergency frequency at approximately 1810.
"Two typhoons from the Quick Reaction Alert (QRA) responded accordingly and authorisation was given from them to go supersonic which resulted in the sonic boom.
"There was no actual threat to the civilian aircraft and they soon rectified their mistake."
It remained unclear last night what action was being taken against the pilot. It is the second time this year that a sonic boom has been created by a Typhoon aircraft.
In January, the MoD confirmed that a loud noise heard by people across the North of England was caused by an RAF fighter jet breaking the sound barrier.
A sonic boom is the sound associated with the shockwaves created when an object travels through the air and breaks the sound barrier.
The noise contains large amounts of sound energy, meaning sonic booms are often mistaken for explosions.