Pakistani authorities have arrested a police officer accused of killing a 27-year-old man and dozens of other suspects in an allegedly "stage-managed" shootout.

The killings in the port city of Karachi sparked outrage on the part of Pakistan's tribal communities, which have long complained of heavy-handed treatment at the hands of security forces.

The officer, Rao Anwar, had gone in hiding after a probe into the Jan. 13 killing of Naqeeb Ullah, a fashion model from the country's Mehsud tribe, found that he had committed no crime. On Wednesday, Anwar voluntarily appeared before the Supreme Court and sought bail, a request which was rejected.

Thousands of people from the tribal communities took to the streets after Ullah's killing, demanding the officer's arrest. Pakistani authorities have vowed to take action.