Johannesburg | At least 12 people died and 45 were injured when a bus overturned on a highway in the South African city of Johannesburg on Tuesday, emergency services said.

Emergency crews were trying to lift the bus back onto its wheels to see if any more victims were trapped underneath it, said William Nthladi, a spokesperson for the city's Ekurhuleni Emergency Management.

The crash happened on a highway near Johannesburg's main O.R. Tambo International Airport. The bus was lying on its side near the edge of the highway. It had been transporting people from the township or Katlehong, east of Johannesburg, officials said.

Nine men and three women died at the scene of the crash, with two bodies still trapped in the wreckage. Officials didn't immediately give the victims' ages.

Nthladi said he also couldn't give details on the extent of the injuries sustained by the people who were hospitalized. The driver was among those taken to the hospital.

No other vehicle was involved in the crash and officials weren't yet able to determine the cause. Police are investigating.