At least 19 children were killed in a bus crash outside the South African capital Pretoria today, emergency services said, after many were trapped inside the burning vehicle.

The minibus and a truck collided on a road between the towns of Bronkhorstspruit and Verena, about 70km from Pretoria.

"It is confirmed 20 children have been killed," Russel Meiring, spokesman for the ER24 emergency medical service, said.

"Paramedics arrived on the scene to find the fire services already in attendance. The fire services had already extinguished the burning vehicle, which was found lying on its side."

South Africa bus crash

Many children were trapped inside the bus and most of the fatalities were declared dead at the site of the accident.

Several other children were injured, with reports that some of them were dragged from the wreckage by people at the scene.

"The children were treated for their injuries and provided with advanced life support interventions before they were transported to various hospitals in the area for further treatment," ER24 said in a statement.

The cause of the collision was not immediately known.

South Africa's ubiquitous minibus taxis are frequently involved in accidents on the country's roads.

"I am saddened. It's a sad day for education," said Panyaza Lesufi, the regional education minister for Gauteng province, who visited the scene of the crash.

Earlier the country's transport minister Joe Maswanganyi had called for greater caution on the roads as he announced that the Easter weekend death toll had increased by 51% to 235 compared to same period last year.

Despite sophisticated road networks, South Africa battles with a high rate of road fatalities blamed mostly on speeding, reckless driving, un-roadworthy vehicles and a failure to use seat belts.