At least 12 people have been killed and some 50 injured after a freight train carrying gas derailed and exploded in northern Italy, officials say.

The wagons jumped the tracks and crashed into several homes, setting off an inferno in the seaside town of Viareggio in the middle of the night.

Several of the victims died when their houses collapsed. There are fears some people may be trapped under the rubble.

Amateur footage shows the immediate aftermath of the accident.