A blast in a pub basement was so loud that regulars feared there had been a car crash, a witness has said.

Norwich Evening News: A carbon dioxide cylinder “went off” in the basement of the Catherine Wheel pub. Photo by Andy Futter.A carbon dioxide cylinder “went off” in the basement of the Catherine Wheel pub. Photo by Andy Futter. (Image: Archant)

Emergency services were called after a gas cylinder's pressure valve ruptured at the Catherine Wheel pub in St Augustine's Street, Norwich, on Wednesday.

It is understood that the carbon dioxide cylinder was used for making up fizzy drinks from syrup.

Andy Futter, 39, of Norwich, was at the bar when he heard the blast shortly before 9pm.

'Everything happened very quickly,' he said. 'I was standing at the bar with a group of friends and there was a sudden bang.

'It was so loud that at first we thought it must be a car accident and dashed to the window to see what had happened.

'It quickly became clear that no accident had taken place outside, and that there was an ongoing hissing sound.

'The noise was coming from the cellar and, following quick thinking from the landlady, the pub was evacuated and the fire brigade was called.'

He said there were around 10 people in the pub at the time, and nobody was hurt.

A man who used to work at the pub was standing near the cellar hatch when they heard the bang, and went to investigate the hissing sound.

'He just went down to see what was happening,' said Mr Futter. 'Despite holding his breath he ended up inhaling some of the carbon dioxide.'

The man, aged in his 30s, was treated by an ambulance crew at the scene and did not require hospital treatment.

Mr Futter added that a barman who was working that night had been in the cellar a few minutes before and it was 'incredibly fortunate' that he was not there when it happened.

Bernice Perkins, landlady of the pub, said there was no damage but the pressure valve had gone wrong and there was a sudden release of gas.

The fire service ventilated the cellar after the incident, with three crews attending.

They used breathing apparatus and a gas monitor.

Do you have a story about a Norwich pub? Email samuel.russell@archant.co.uk