An explosion targeting a tourist bus has injured at least 16 people near the Grand Egyptian Museum, next to the pyramids in Giza. South African tourists are among the injured. Most of those hurt suffered minor injuries, while three were treated in hospital, officials say. A device went off close to the museum fence as the bus was passing. It is not yet known who was behind the bombing but Islamist militants have attacked tourists in Egypt in the past. In December, three Vietnamese tourists and a local tour guide were killed after a roadside bomb hit their bus. What do we know about the blast? A witness, Mohamed el-Mandouh, told Reuters news agency he had heard a "very loud explosion" while sitting in traffic near the site of the blast, which is close to the capital Cairo. The blast hit the bus which was carrying 28 passengers, Egyptian Tourism Minister Rania A Al Mashat said. Images taken after police cordoned the bus show a vehicle with windows blown out or shattered, and glass littering the aisle inside. A private car was also damaged behind the bus. Image captionBroken glass lay on the floor of the bus after the blast According to state-run broadcaster Nile News TV, the bus was carrying 25 South African tourists and a security source confirmed for Reuters that South Africans had been aboard. Seven South African tourists and 10 Egyptian civilians were injured, Nile News TV says. The tourism minister said all of the people affected by the blast were being "fully supported in their onward travels".