Thirteen vehicles, including a truck that overturned, have been involved in an accident on the N4 highway between Witbank and Middleburg on Monday, Mpumalanga police said.
"We are not sure what the cause is but we think it is heavy smoke from fires on both sides of the highway obstructing drivers' vision," said Captain Klaas Maloka.
"At the moment we can only confirm that three people have been injured."
He said police and emergency personnel were at the scene and by 3.30pm were still trying to verify details of the accident which happened at around 2pm.
"We don't know if anyone died and the number of injured may still increase as we get more information," he said. - Sapa