A huge explosion at a butane gas depot in south-eastern Nigeria left "tens" of people dead, Nigeria's president says. The fire raged for more than five hours before being extinguished. Witnesses said the bodies of workers and customers at the depot in nnewi in anambra state had been burned beyond recognition. Many customers had gone to the plant to fill up their gas bottles to cook meals on christmas day. Staff inside the plant are reported to have been trapped. The ferocity of the blast also damaged houses in the surrounding area. Passers-by were also caught up in the explosion, reports say.