People have used social media to debate what is causing the late-night series of loud bangs heard across north Norfolk.
The noises shook up residents in Cromer, Holt, Roughton and North Walsham but questions linger over the source.Residents from the towns and village reported hearing the mystery bangs between 3.15am and 4am on Monday, August 5.
Rachael Verlander from Cromer said on Enjoy Cromer More's Facebook page: "Bit of a strange one but did anyone else hear what sounded like three gun shots at the top of Norwich Road last night?
"Heard the shots (very loud, definitely not a car back firing, or fireworks) then a car drive off. Me and my husband both heard it, so no I wasn't dreaming!"
With questions arising over the source of the noise, here are seven things the mysterious bang could be.
1 - Boat distress flare
Some residents thought the noise may have been a distress signal from a boat. Boats have two main types of distress signals, pyrotechnic and non-pyrotechnic. Pyrotechnic signals create a chemical reaction that produces a flame or light, smoke or sound. Some common types include parachute flares, handheld flares and floating smoke signals.
Non-pyrotechnic signaling devices last longer than pyrotechnics and provide prolonged signals for rescuers.
But the Coastguard has confirmed it had no incidents in Norfolk on Monday morning.
2 - Fireworks
Fireworks could be a very simple explanation for the loud bangs being heard across north Norfolk. With people using them for anything from fun in their back garden to wedding proposals and birthdays, it is a strong potential explanation.
3 - Car backfiring
A loud bang from your exhaust pipe is the sound of a backfire, which happens when unburned fuel comes out of the engine and ignites in the tailpipe.
As the noise was heard in several different locations within the same hour of the morning, it remains a possible answer.
4 - Sonic boom
A sonic boom is a loud sound caused by shock waves created by any object that travels through the air faster than the speed of sound.
The noise of a sonic boom is not heard in all directions from the object and is not only heard at the moment the object breaks the speed of sound.
With Royal Air Force bases all around Norfolk, a sonic boom would be a valid explanation but the RAF said it had no operations on Monday morning.
5 - Military exercise
A lot of unexplained loud noises can be put down to military training, either at army or naval bases or in remote areas that are regularly used for such exercises. Multiple areas across Norfolk such as Thetford, RAF Lakenheath and RAF Trimingham could have been in use for military training.
6 - Red car throwing firecrackers
Anybody else seen this tale in the comments? Several people have reported seeing a red car with firecrackers being thrown out of the window.
A firecracker is a small explosive device primarily designed to produce a large amount of noise, especially in the form of a loud bang. The miniature fireworks were banned in the UK in 1997.
7 - Coincidence or panic
People commented saying they thought the bangs sounded like gun shots. In this age of social media, panic can spread, and once one person says they have heard a loud bang dozens of others can follow suit.
While some may genuinely be looking for an explanation for what they have heard, others will just want to add to the hysteria and will claim to have heard noises just to see how the story grows.
A spokesperson from Norfolk Police said: "We received two calls, one at 3.20am and another at 3.27am for reports of two loud bangs in the Cromer area."
"Officers went to investigate but did not find anything."
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