Cairo, Egypt (CNN) At least 17 people were wounded in an explosion that targeted a tourist bus on its way to visit Egypt's Giza pyramids, a doctor at the hospital where they are being treated told CNN.

The bus was carrying 25 South African citizens, Egypt's state-run Ahram daily reported. A device exploded near the bus, while the windshield of another vehicle was damaged.

Tourists arrived in Cairo airport at noon Sunday and were on their way to visit the Great Pyramids of Giza when the blast hit their bus, a tour guide and one of the tourists told CNN outside Al-Haram Hospital where they were taken.

"As soon as the tour guide said this is the pyramids, the explosion happened," a woman wearing a blood-stained white T-shirt told CNN on her way out of the hospital. The interview was interrupted by security before the woman could provide her name.

Ten tourists and seven Egyptians were brought to Al-Haram Hospital with minor injuries, Ahmed Bassiouny, a medical doctor, told CNN. Ten patients have left the hospital, while seven were transferred to another hospital.

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