ASWAN (Updated) - Eight American tourists were killed and 21 others were injured Sunday when their bus collided with a truck near the southern Egyptian city of Aswan, a security official said. "The bus, which was carrying 37 tourists from the United States, was headed to the ancient Egyptian Abu Simbel temples when it collided with a damaged truck parked on the side of the road," the official said. He said that six of the dead were women. The bus driver and a tourguide were also injured in the accident, which occurred early in the morning about 30 kilometres (18.6 miles) from Aswan. "Four tourists were in critical condition," the police official said, adding that the injured were taken to a military hospital in Aswan. The US Embassy in Cairo said in a statement that it was "deeply saddened by the traffic accident in Aswan that has led to deaths and injuries among American tourists". It did not provide a toll. It said the injured were being moved by military transport to Cairo. Later in the day, Minister of Health Dr Hatem el-Gabali ordered two ambulance helicopters to airlift the injured to Cairo's Nasser Institute to continue their treatment. "The two helicopters landed at Aswan Airport and carried five cases to Cairo, while others insisted to have their treatment in Aswan," said Mohamed Salah, the Deputy Minister of Health in Aswan. He added that most injuries were broken bones of lower limbs and necks. Seventy-nine tourists on board two other buses in the convoy were unharmed, Egypt's official Middle East News Agency (MENA) reported. Traffic accidents occur frequently in Egypt, often because of poor road condition and lax regulations. The US State Department warns on its website that travelling on Egyptian highways can be dangerous. Embassy officials are prohibited from travelling outside Cairo after dark because of driving hazards, according to this warning. The bus's operator was the Misr Sinai tour company, a thirty-year old enterprise founded and partially owned by the Egyptian government. Company officials declined to comment. Eighteen French tourists were injured when their bus overturned on the same two-lane desert road last January. The 3,000 year-old granite Abu Simbel temples are a popular tourist attraction. They were relocated to their present location, about 300 kilometres from Aswan, in the 1960s to prevent them from being submerged by rising waters from the Aswan Dam which was under construction. About 8,000 people die from traffic accidents each year in Egypt, mainly due to reckless driving and poor roads.