JOHANNESBURG — The footage is shaky but unmistakable. A slender black man dressed in a red T-shirt, black pants and sneakers is tied to the back of a police truck. He kicks. He writhes. The vehicle pulls away, dragging the man behind it. Police officers run along with him. Cellphone cameras snap away.

“What did he do?” bystanders shouted.

“It was him who started it,” a police officer replied.

Late Tuesday night, the man, who has since been identified as Mido Macia, 27, a taxi driver from Mozambique, died of head injuries at the Daveyton Police Station, 27 miles southeast of here.

In South Africa, where violent crime, vigilante attacks and police brutality are daily fare, the video, captured on a cellphone and first published by The Daily Sun, a local tabloid, has incited outrage for its brazen and outsize cruelty.

“We come across a lot of cases of police brutality,” said Moses Dlamini of the Independent Investigative Directorate, which investigates police crimes, in a television interview. “The police don’t even care that people are watching.”