JOHANNESBURG (AP) — A bus overturned on a South African highway Tuesday and passengers were thrown out of it, killing at least 12 people and injuring 45 in Johannesburg, 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.

“On arrival we found patients lying across the road," Nthladi said.

The bodies of some of the victims lay on the highway near the bus and were covered with silver blankets. Two bodies were still trapped in the wreckage, Nthladi said. Handbags, a lunch box and a water bottle were visible among the belongings.

“We are lost for words. This is a disaster,” said Andile Mngwevu, a local city councillor who went to the scene. “To see so many bodies lying around is quite saddening, and the city really feels for the families who would have expected to see their loved ones return home later today. Our hearts are extremely heavy right now.”

The early-morning 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.

Nthladi said 12 people were declared dead at the scene of the crash by paramedics. A fire engine, ambulances and pathology vans were deployed.

Nthladi said he couldn’t give exact details on the extent of the injuries but said they ranged from serious to critical. 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.