A South African freight train derailed and plunged into a river Tuesday morning, leaving four people injured.

The train plunged into the Amanzimtoti River near the eastern port city of Durban, the South African Press Association quoted local emergency department as saying.

The sand base under the track was eroded by the raging river, causing the running train to lose its balance, local emergency department spokesperson Chris Botha said.

Four train staff members, who were severely traumatized, were sent to a nearby hospital for treatment, according to the report.