JOHANNESBURG — At least 16 people have been killed and 20 others injured when a bus transporting passengers to South Africa’s Eastern Cape province overturned in the early hours of Thursday.

According to authorities, the bus was transporting 78 passengers from the city of Cape Town in the Western Cape to Idutywa in the Eastern Cape.

“It is alleged that the bus swerved to avoid colliding with a delivery vehicle when the driver lost control and the vehicle overturned,” said Road Traffic Management Corporation spokesperson Simon Zwane.

While initial reports indicated that nine people had been killed, further investigations on the scene revealed a total of 16 fatalities.

Those injured were transported to the hospital in the town of Worcester, about 120 kilometers (75 miles) from Cape Town, while at least 43 passengers refused any medical treatment.

“The cause of the crash will be subject to the ongoing investigation by the RTMC and the South African Police Services,” said Zwane.

Authorities have warned motorists to be extremely cautious when driving during the winter period due to fog causing poor visibility.

The roads can become extremely dangerous during this period because of fog, smoke, black ice and poor visibility.

This is the second fatal bus crash in South Africa this week after a bus driver was killed when a bus transporting Malawians to the Beitbridge border in Limpopo overturned on Wednesday.