A rugby player in his 20s has died during a game between Wisbech and Diss.
It is understood that the Wisbech player team went down during the match on Saturday afternoon and despite efforts of ambulance staff to resuscitate him on the pitch, he passed away.
The game Eastern Counties First Division match at the Chapel Road ground was abandoned.
Roger Pierson, from the Eastern Counties Rugby Union, said there had been a collision but that no head contact had been involved.
He said two of the Diss players who were medically qualified immediately went to the aid of the injured man but that he died on the pitch.
Mr Pierson described the tackle as a "rugby incident" and said everything was being done to support all the players involved.
"The RFU and the Injured Players' Foundation are already involved and that help will be offered to Wisbech and also to Diss rugby," he said.
A further statement is expected from the Rugby Football Union.
The East of England Ambulance Service said a player had suffered a cardiac arrest during the match.
Responders carried out CPR and used a defibrillator but the man "could not be resuscitated".
An EEAST spokesperson said: "Our thoughts are with their family and friends at this tragic time."
Two ambulances, the air ambulance and the fire service were called to the scene.
Hundreds of messages of support and condolence have poured in from rugby clubs around the region and across the country.
Norfolk RFU posted a message on Facebook saying: "Our thoughts and prayers are with our family and friends at Wisbech Rugby Club."
Norwich Rugby Club said: "The deepest condolences if everyone at Norwich Rugby Club to Wisbech Rugby Club and Diss Rugby Football Club and all affected by the tragic events of yesterday afternoon."
Dereham Rugby Club posted: "From everyone at Dereham, we pass on our condolences to Wisbech Rugby Club & the family & friends of the player who sadly passed away playing the game we all love yesterday. We also extend our thoughts to everyone at Diss Rugby Football Club in what must be a difficult time
"Our rugby family sends our condolences and love."
West Norfolk Rugby Club added: "Thoughts are with you all from Wests" while Holt RFC posted: "Thoughts are with you all from Holt RFC" and Swaffham RUFC said: "Condolences from us all at Swaffham."
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