South Africa's police watchdog is investigating the death of a Mozambican taxi driver who was allegedly handcuffed to the back of a police van and dragged through the streets.
Video footage taken by a bystander of the incident, near Johannesburg, has been shown in the local media.
A spokesman for the Police Investigative Directorate said he was "shocked" by the footage.
Rights groups often accuse South African police of brutality.
Local media reported that police initially assaulted the 27-year-old Mozambican, a taxi driver, accusing him of parking his vehicle incorrectly in Daveyton, east of Johannesburg.
The video shows a large crowd gathering, as uniformed policemen tie him to a van, dragging him as they drive away.
'Police vigilantes' He was later taken into custody, where he died, local media report.
"We are investigating an incident involving the death of a man, allegedly at the hands of the police. We are shocked by the footage which has been released," Independent Police Investigative Directorate (IPID) spokesman Moses Dlamini was quoted by AFP news agency as saying.
"The circumstances surrounding his death are still allegations... Let's find out what really happened.