Twenty nine people have been killed after a bus collided with a truck in South Africa's Mpumalanga province north-east of the capital, Pretoria.
Scores of passengers were also taken to a nearby hospital after the collision on Monday night, officials said.
President Jacob Zuma said he was shocked by the death toll: "This carnage must stop. It is completely unacceptable."
South Africa has one of the highest numbers of road accidents in the world.
The BBC's Milton Nkosi in Johannesburg says the accident happened on the notorious Moloto Road.
Details are sketchy but it is believed that a bus ferrying passengers collided head-on with a truck which had veered into the opposite lane, he says.
The accident occurred in low visibility conditions when it was pouring with rain.
According to South Africa's Eyewitness news website, two other vehicles piled into the bus and truck.
Transport Minister Dipou Peters has ordered a high-level investigation to determine the exact cause of the crash.
Around 50,000 people commute to work in Pretoria daily along the narrow and potholed route, the AFP news agency reports.