A man remains in a critical condition following a fight at a Morrisons supermarket in Wymondham.
Norfolk police said a man in his 20s, who is from the local area, was involved in an altercation inside the shop on Monday evening.
Officers were called to the scene shortly before 8pm after concerns were raised for the welfare of a man inside the shop.
Police did not give details on the extent of his injuries or how he had received them, but said four people had been arrested.
He was treated by paramedics before being airlifted to the Norfolk and Norwich University Hospital by the air ambulance.
A police spokesman said he remained in a 'critical condition'.
Three men, aged in their 20s to mid 40s, and one woman, aged in her late teens, have been arrested in connection with the incident.
Police said they are all from the local area. It is understood that all those involved in the incident are known to each other.
'Detectives continue their enquiries into the circumstances surrounding the assault, but can confirm that there were not any weapons used during the incident,' a police spokesman said.
The supermarket remained closed until shortly after midnight to allow investigations to be completed.
It has reopened this morning and police are no longer at the scene.
A Morrisons spokesperson said: 'A serious incident involving a member of the public took place at our Wymondham store last night and we have been helping the police as they investigate. Nobody else was hurt. The store has reopened this morning.'
An eyewitness shopping at the store said: 'There was a commotion in the store and the next minute I saw CPR being done on a man. It was very traumatic, there were lots of kids and families around. The store was evacuated.'
Anyone with information regarding the incident are asked to contact Norfolk Police on 101 or alternatively call Crimestoppers anonymously on 0800 555 111.
Police said it was not linked to a stabbing in the town on Sunday, July 16.
Community reaction
Wymondham county councillor Joe Mooney saw the air ambulance arrive as he watched from his home opposite Morrison's supermarket at Orchard Way.
He said: 'I heard the noise overhead and saw the air ambulance arriving close to the road.
'In 15 years of living here I have never seen that sort of thing before.
'I am shocked by the incident. This is a very quiet area and the crime level in Wymondham is very low. It is mostly anti-social behaviour.
'I spoke to local people this morning and they are quite shocked that this has happened in our town.
'Although these things can happen anywhere, it is a shock when they come closer to home.
'I would strongly encourage anyone with any evidence about the incident to please report it to the police.'
From the scene this morning
The store has reopened as normal this morning and there is nothing to signify that anything happened last night.
A 50-year-old woman, who was shopping at the store today, but who did not want to be named, said: 'I'm just glad my grandchildren weren't here because my daughter is always in here.
'I was shocked to hear. It's not good.
'My daughter rang me and asked if I'd heard about it. I couldn't believe it.
'There's never anything like that or never used to be.'
A 66-year-old shopper said: 'I'm shocked. Especially here - you don't think about it in your own town.
'I've got a family and you think what if one of them was involved.
'You never know what's going to happen.'
Another shopper, who wanted to remain anonymous, said: 'I heard the air ambulance going over.
'I'm shocked to hear what happened like everyone is.'
• Did you witness the incident? If so contact the reporter at andrew.stone@archant.co.uk.
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