The sonic boom caused by RAF Typhoon fighter jets left many residents in Thetford wondering if there had been an explosion.
The noise, which happened at around 8.40am, shook buildings and windows and saw people leave their businesses and walk onto the high street to see what had taken place.
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Mark Bedford, headmaster of Thetford Grammar School, was at the Thetford Business Forum meeting in the Bell Hotel when the bang happened.
He said: 'The building shook and I was immediately concerned about the children, staff and parents at school.
'I instantly left to check the school was safe. People on Bridge Street were asking what was going on.
'A police officer then informed us that he believed it was a sonic boom.'
Dean Honour, the manager of Hughes in the town, said: 'It was a big of bang. The windows shook. At first we thought it sounded like somebody was on the roof.
'I then got a text from my daughter at the Thetford Academy saying there had been an explosion at school but she was in class. When I looked online I saw it was a sonic boom.'
Pupils at the town's Bishop's Primary Academy were evacuated as a precaution because staff were unsure of what had caused the bang.
A spokesman for the school said senior leadership were not present when the bang was heard and the decision was made to evacuate the pupils while checks were made.
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