The air ambulance has now left the site, but the RAF search and rescue helicopter remains there alongside police and coastguards, and both Bridlington and Flamborough lifeboat crews launched at around 1.45pm.
A statement from Humberside Police said: “Police, coastguarduard and ambulance service attended the area right away and a search was carried out which resulted in the helicopter being located in the sea off the coast of Flamborough near the lighthouse.
“An area has been cordonend off while the emergency services and coastguard continue their work.
“Initial inquiries are being made in order to try and establish the circumstances which led to the helicopter coming down.
Members of public and the media are asked to stay away from the area until further notice due to the site being close to dangerous cliff edges and there also being a quantity of what appears to be aviation fuel in the water around the crash site making it potentially unsafe at present.”
It is understood the helicopter was travelling to Humberside Airport and that a team from the Air Accidents Investigation Bureau is on its way to Flamborough.
Rod Marwood, course chairman at Flamborough Head Golf Club, said: “The helicopter was flying around the north side of the course. I don’t usually take any notice of them.
“I didn’t this time until the engine started to make a terrible noise. It looks as though it was trying to land on the course or on the cornfield next to the course.
“Some of the golfers were only 50 or 60 feet away from where the crash was.”