Two Vietnamese tourists were killed and 12 other people were injured when a bomb blast hit their bus on Friday less than four km (2.5 miles) from Egypt's world famous Giza pyramids, authorities said.

Ten of the injured were Vietnamese tourists and two were Egyptians – the driver and a tour guide, an interior ministry statement said, Reuters reported.

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The bus was hit by an explosion from an improvised device hidden near a wall on Marioutiya street at around 1815 (1615 GMT), the ministry said.

About two hours later the bus could be seen behind a police cordon with one of its sides badly damaged and the windows blown out, a Reuters reporter said.

Dozens of police and firefighters were at the scene, on a narrow sidestreet close to the ring road.

Police are investigating, the ministry said.