At least 20 dead in Argentina police bus accident: mayor

At least 20 people were killed and several more injured when a bus carrying police officers drove off a cliff in northwestern Argentina, a local mayor said.

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