A spokesman for Norfolk Police said:
"The man was retrieved from the water and was taken to Addenbrooke's Hospital by air ambulance for treatment. He is currently described as being in a critical condition.
"Police and the Health and Safety Executive are carrying out a joint investigation into the incident."
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Two robbers who attacked a man after threatening him with a chisel in Luton have been jailed for a total of 13 years
A dry day with plenty of sunshine across the region. Feeling cooler near the coast but inland temperatures will be well above average.
A chilly night to come with a mixture of low cloud, mist and fog. More sunshine will return tomorrow.