Four people were injured in Quetta's Mannan Chowk area when two groups clashed over a land dispute on Saturday morning.
Video footage shared widely on social media sites showed attackers using knives and guns to injure multiple victims in an area categorised as a high-security zone.
Eye-witnesses said that despite pleas of help from the injured, police personnel present at the scene remained silent spectators, with some even fleeing from the spot.
The deputy inspector general of police, Quetta, Abdul Razzaq Cheema, said in a statement that the Mannan Chowk incident was the result of a "tribal dispute" between two groups.
He added that strict legal action would be taken against police officials who showed negligence in averting the violence.
Police were later deployed in the vicinity of the warring tribesmen to avoid another untoward incident, and raids will be conducted to apprehend those involved in the attack, Cheema said.