Three people, including two robbery suspects and a police officer, have been killed following "vigilantism" in Piet Retief, Mpumalanga police said on Sunday.
Police spokesperson Colonel Brenda Muridili said Piet Retief police members were called to a scene of alleged mob justice on Saturday.
The public were accusing the two suspects of committing robberies in and around the town's taxi rank.
"As the [police] members were trying to calm the angry mob, a shot went off from the crowd and hit Sergeant Patrick Mthobeni. He was rushed to hospital where he was declared dead on arrival."
Muridili said that when the mob dispersed, one of the robbery suspects was "found lying dead on the ground and the other one was rushed to hospital where he also passed away".
Acting National Commissioner Lieutenant-General Bonang Mgwenya condemned the incident.
"Vigilantism is tantamount to undermining the authority of the state. The police are mandated by the Constitution of the Republic to uphold the rule of law. Those community members who participated in an act that left a police officer and two people dead, will be traced and arrested."
Mgwenya said the province instituted a 72-hour activation plan "to ensure that all relevant role players have been mobilised".
Cop shot several times
In a separate incident, Muridili said an officer that attended the mob justice incident with Mthobeni, Constable Nkosingiphile Ninela, arrived home after and became embroiled in an altercation with a relative.
"It is alleged that the relative used the member's service firearm and shot him several times in the back. Constable Ninela is in hospital where he is reported to be in a critical condition while his relative has been arrested for attempted murder."
Mgwenya wished the officer a speedy recovery.
"I am glad that the person responsible for the attempted murder of Constable Ninela is behind bars where he will be facing the full might of the law," she said.
Anyone with information that can lead to the arrest of the perpetrators is requested to contact the SAPS Crime Stop number ?08600 10111.