The emergency services were called at 7.30pm following reports the aircraft- thought to be an Augusta-Westland - had come down in Gillingham, near Beccles, Norfolk.
Norfolk Police said the area of the crash site has been cordoned off.
It is not known what how many passengers were on board, but police confirmed there had been four fatalities.
The site is 45 miles from the spot where four crew members died when a US military helicopter crashed in Norfolk on a training mission in a nature reserve in Cley-next-the-Sea, Norfolk.
Tonight, Roland Bronk, owner of The Swan House restaurant in Beccles, said it was "very foggy" in the area at the time of the crash.
Mr Bronk said he heard customers talk about "a lot of police activity and ambulances".
One Twitter user, @andrew89mufc, said thick fog might have played a part in the crash, adding: "Helicopter crashed very close to my house in Gillingham tonight. I heard it flying over the house.
"I live in Worlingham on Park Drive. My garden backs onto the woodland leading to Gillingham. I heard a helicopter circling the house for about 15 mins at around 7:45. This may have been air ambulance or police searching though."
He added: "Can't see my hand in front of my face. No sign of scene of crash."Taxi driver Mark Murray, 22, from Beccles, said: "There is a large stately home nearby and you often see helicopters coming and going from there.
"When they have a game shoot the guests often all arrive in separate helicopters. We don't know if that is linked, but that's the only helicopter activity we see in this area."
A spokeswoman for East of England Ambulance Service said: "We got called to reports of a helicopter crash near Beccles and we sent several resources to the scene, including doctors."
It is not yet known whether fog, which beset much of England earlier today, played a factor in the crash.
In January, a Pave Hawk from RAF Lakenheath was taking part in a low-flying training exercise when it came down in a nature reserve in Cley-next-the-Sea in the county.
All four American crew members were killed in the crash. Residents described hearing a "'heavy and very unusual" noise from the helicopter seconds before the crash.
The aircraft was carrying munitions at the time of the crash and police subsequently cordoned off the area at they investigated the nature of the weaponry, which was later found to be bullets.
An air accident investigation team is on the way to the scene.