Bus drives off cliff in Argentina, 20 dead

At least 20 people have been killed and several more injured after a bus carrying police officers drove off a cliff in northwestern Argentina.

The cause of Monday's predawn accident, in which the bus with 60 police officers on aboard plunged some 15 metres into a dry riverbed, was unclear, said Gustavo Solis, mayor of Rosario de la Frontera in Salta province.