Two drivers died in a three-vehicle pile-up on the N4-highway, about 10km east of Nelspruit in Mpumalanga on Sunday afternoon.
The driver of a minibus believed to have been ferrying passengers from Ivory Park in Tembisa, Gauteng, to Mozambique, burnt beyond recognition after his vehicle burst into flames.
The mini-bus was said by police to have been carrying a container with 20 litres of petrol. Police said the fuel caused the fire when it spilled during impact.
The driver of a bakkie that was also involved in the accident, also died and scores of other people were rushed to Rob Ferreira hospital in Nelspruit.
Inspector Dawie Pretorius confirmed that the two drivers died on the scene, but he did not immediately have the number of casualties.
"I can confirm that two drivers died on the scene, but until I have spoken to the investigating officer, I won't know how many injured people were rushed to hospital," said Pretorius on Monday.
He said police were still investigating how the accident happened, but witnesses told Sowetan that the minibus taxi from Gauteng had lost control before it collided with a minibus taxi from Malelane to Nelspruit.
"The minibus from Malelane then collided with a bakkie that was thrown out of the road and the one minibus taxi caught fire when 20-litre containers of petrol were flung away," said Peter Majola, a motorist who witnessed the accident.
He said some of the petrol containers remained in the vehicle and added to the ferocity of the fire.
The driver of the minibus was trapped in the burning vehicle and spectators could only watch him perish in the fire before the fire brigade arrived and put out the flames.
The N4-highway had to be closed for about three hours and traffic was diverted via Magugu suburb road, while the accident scene was being cleared.
The accident happened at a place where a big sign with the words "high accident zone" is clearly mounted on either side of the road.
Mpumalanga provincial police spokesman, Superintendent Abie Khoabane warned that it was against the law to transport petrol in a vehicle not designed for the purpose.
"It is against the Safety Act to transport petrol in a vehicle that has not been designed for that purpose and I believe the vehicle would not have caught fire if it was not for the petrol," said Khoabane yesterday.
Police said the names of the dead could not be released as they were still struggling to trace their next-of-kin.
Mpumalanga transport department spokesman, Joseph Mabuza, declined to comment and referred all inquiries to the police.