A bus overturned in an area of Johannesburg near South Africa’s main airport early Tuesday, killing at least 12 people, city officials said, with dozens more injured. The bus was carrying more than 50 people to work when it crashed on a busy road near Johannesburg’s OR Tambo International Airport, officials said. Twelve people were killed and 45 others hurt, they said in a statement. “We are lost for words. This is a disaster,” Ekurhuleni city transport official Andile Mngwevu said. The cause of the accident was not immediately known. It forced the closure of the highway leading to the airport. Images from the scene showed the bus on its side. A survivor of the accident told Newzroom Afrika television that it appeared the bus was speeding. Despite sophisticated road networks, South Africa battles with a high rate of road deaths blamed mostly on speeding, reckless driving, unroadworthy vehicles and failure to use seat belts. Four school children were killed Monday and five others injured when two vehicles collided around Ekurhuleni, which lies east of Johannesburg. At least nine people, including a four-year-old child, were killed last week when their bus careered into a ditch in the eastern province of KwaZulu-Natal.