Derbyshire Fire and Rescue received a number of calls around 3.30pm today after reports of an explosion at a disused Thornton's factory in Belper.
People were reported to be inside the building at the time of the explosion but everyone is accounted for.
Fire crews are now damping down and the fire is under control.
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Dry and largely clear for most overnight with winds easing. Temperatures will fall close to freezing for many so a frost is expected.
Remaining cloud and rain should soon clear eastwards during the evening, leaving a dry remainder of the night.