A Papua New Guinea police officer is being held in custody following a road accident that left two people dead last week in Alotau.
The capital of Milne Bay province went into lockdown for two days after a public protest over the incident spiralled into unrest.
A police spokesman said the situation in Alotau had returned to normal and the policeman in custody is to be formally arrested and charged once investigations are complete.
The spokesman said provincial police had talks with the relatives of the 39-year-old mother and her five-year-old child who were killed.
Another young mother and her child were seriously injured in the accident involving a vehicle under the command of the Lae Water Police whose members were in transit to Port Moresby for the APEC summit.
Police manpower has been increased in Alotau to maintain law and order.
Meanwhile, the Acting Provincial Police Commander Chief Inspector George Bayagau offered some explanation for how the protest by family and friends of the victims descended into unrest.
"The relatives of the deceased were stopped by the police officers who talked to them on several occasions not to do a protest march but they did not listen to the instructions," he said.
"This resulted in four protesters being wounded and admitted to the Alotau General Hospital when police fired shots to disperse the crowd."
Mr Bayagau said police took the action they did because they received intelligence reports that armed criminals were planning to take advantage of the protest to create chaos and loot businesses.
Earlier, the deceased relatives had blocked the Golenai bridge to Kwaini, on the outskirts of Alotau, where the accident occurred.
The provincial commander explained that police used a backhoe to clear the road blockage of trees and stones
Meanwhile, a police investigation continues into the accident, with a Criminal Investigation Division team dispatched from Port Moresby to the province to deal with the case.