Fire crews were called to a blaze at a commercial building in an industrial estate on the outskirts of Norwich Wednesday afternoon. The fire broke out at about 4.15pm in Rackheath industrial estate. Large plumes of smoke could be seen billowing from the workshop unit. Four appliances and a water foam unit attended the scene. An eyewitness said it sounded like fireworks were going off and that the roof of the unit has since caved in. It was brought under control by 4.45pm.