Masked raiders stage armed robbery at jewellery shop

Video shows a stream of people wearing masks covering their faces entering the shop (Screengrab/AP)

At least two dozen people wearing masks and some carrying pick axes and handguns have smashed jewellery cases and made off with bags full of items during a robbery at a San Francisco Bay area store, authorities said.

Video from the robbery in the US state of California on Monday shows a stream of people wearing masks covering their faces entering the shop and using the pick axes to crack the glass cases and clear them out.