Thieves threatened two young boys before stealing their bikes outside a supermarket in Costessey.
Police said the victims, aged 10 and 13, were approached by two teenage boys outside Sainsbury's at Longwater Retail Park on Sunday afternoon.
The victims were threatened before having their bikes - a red 'Jamis' 27' bike and a black and yellow 29' bike - stolen.
The thieves, thought to be in their mid-teens, escaped in the direction of the McDonalds restaurant.
Norfolk police said one of the suspects was wearing a grey hooded top and black jogging bottoms, while the other was wearing dark jogging bottoms, gold and black trainers, a black hat with built-in goggles and an Adidas bag.
The incident happened shortly after 2.30pm on Sunday, March 31.
Officers are keen to speak to anyone who witnessed the incident or was parked at the supermarket and may have dashcam footage.
• Anyone with information should contact PC Amy Durrant at Wymondham Police Station on 101 quoting reference 36/21597/19 or call Crimestoppers anonymously on 0800 555 111.
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