An Air India passenger plane was forced to make an emergency landing at Stansted Airport after a bomb threat.
The Boeing 777 airliner was escorted into London by two RAF Typhoon fighter jets.
The RAF confirmed it had scrambled the jets due to a bomb scare on board.
Air India posted in a now-deleted tweet that it had made the precautionary landing in London due to a "bomb threat" shortly before 10.30am today.
A sonic boom was widely felt and heard in Derby around the same time.
An RAF spokesman said: "The RAF can confirm QRA Typhoons were launched this morning from RAF Coningsby to intercept a civilian [aircraft].
"The aircraft was escorted to Stansted. The Typhoons transited at supersonic speed for operational reasons; any inconvenience caused to local residents is regretted.”
Essex Police said they are at the airport making enquiries after reports of a security alert.
Did you see the RAF jets or were you on the flight? Email webnews@mirror.co.uk
Stansted Airport released a statement confirming the Air India Boeing 777 had been diverted at 10.15am and had "landed safely with Essex Police in attendance."
A spokesperson tweeted: "It is parked on an isolated stand away from the normal airport operations.
"Our runway has now re-opened and is fully operational. We are very sorry for any delays and disruption caused by the incident, but our first priority is always the safety of passengers and staff.
"Thank you for your patience."
The Air India aircraft had been heading from Mumbai to Newark.
The airport added shortly before 11am that its runway had reopened and is fully operational.
"We are sorry for any disruption caused by the incident and would like to thank you for your patience," Stansted tweeted.
A route map online showed how the Air India flight turned back and landed in London.
It came as multiple people across Derby reported experiencing what felt like an 'explosion' this morning.
Police asked those with information to call 999, before telling Mirror Online that the sound was a 'sonic boom' and referring further enquiries to the RAF.
On Twitter it initially speculated the loud blast may have been an earthquake or a 'pressure wave'.
It comes just days after two RAF Typhoon jets were scrambled to escort a Jet2 plane as it returned to Stansted.
The 'sonic boom' sensation was widely reported around Essex.
A woman was arrested after allegedly trying to open the cockpit door on the Jet2 flight from Stansted to Dalaman in Turkey on Saturday, forcing the aircraft to return to the Essex airport.
A Royal Air Force spokeswoman said of the earlier incident over Essex that the Typhoons were scrambled form RAF Coningsby to escort a commercial flight into Stansted due to reports of a "disruptive passenger."
The Mirror has not yet been able to reach Air India for an update on the latest incident.
