A suspected sonic boom has been reported in the skies over Norfolk and Suffolk.
People have described the sound of an explosion and buildings shaking during the event at about 16:30 GMT.
Simon Boston, who was at a petrol station in Necton, near Swaffham, Norfolk, said the “huge boom” sounded like a car crash.
The Ministry of Defence (MoD) said there had not been any RAF Quick Reaction Alerts issued in the area, and RAF Typhoons had not been deployed. The United States Air Force (USAF) has been contacted for comment.
The BBC has been contacted by people who said they heard the boom in and between Norwich and Ipswich.
Many people have also taken to social media to share their experiences.
Boston added: “I initially thought it had been a car crash on the A47.”
A sonic boom occurs when an aircraft travels faster than the speed of sound, generating shockwaves that rapidly compress and decompress the air.
While the speed of sound varies depending on the altitude, it is about 660mph (1,060km/h) at 60,000ft (18,300m).
Jemima Miller, 22, from Norwich, said she heard jets above her as she walked her dog.
“I thought nothing of it until it was so loud I could no longer hear my music, and then followed two big bangs that shook the area I was walking in,” she said.
“I could see the plane above and thought I was being shot at.”
Spencer Smith added the boom shook his front door in the city.
Supersonic flight over land is rare and only authorised in exceptional circumstances.
Occasionally such flights are cleared as part of Operational Quick Reaction Alert missions in the defence of the United Kingdom.
The MoD spokesperson said: “I can confirm that there was no RAF Quick Reaction Alert today, which would have meant RAF Typhoons taking off from either RAF Lossiemouth or RAF Coningsby.”
It is thought that the aircraft involved could have been from the USAF, but the MoD does not comment on the air activity of other nations.
