A man in his 40s has been arrested on the outskirts of the city.
Officers were called to Magdalen Street near the junction of Cowgate Street shortly after 12.30pm on Wednesday.
This was following a report of a theft from a shop.
A spokeswoman for Norfolk Police said: "A man aged in his 40s was arrested in Magdalen Street in connection with the incident and taken to Wymondham Police Investigation Centre for questioning.
"He remains in custody."
An eyewitness said: "I saw police arrive at the scene with the sirens on. It caught my attention because there was a lot of shouting and there was someone on the floor."
The eyewitness then watched the van drive away a short time later.
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