Media playback is unsupported on your device Media caption Footage from the scene shows the building both on fire and encased in ice

A warehouse in the US city of Chicago, which was encrusted with ice after firefighters apparently extinguished a blaze on Wednesday, is again on fire.

Reports said the fire had engulfed the whole building for a second time.

Water used to put out the initial fire had frozen in the extreme cold, leaving a thick crust of ice.

Fire officials say the structure should be pulled down, as it has already partly collapsed and the weight of the ice would have made it more unstable.

Temperatures in the city are currently falling to -7C (19F) at night.

The cold has also hampered efforts to put out the fire. About 170 firefighters battled it from Tuesday evening into Wednesday morning, their hoses and hydrants freezing.

It is not clear what caused either of the fires, but the warehouse is said to be full of old timber.