Gunmen in Brazil opened fire outside a bar in the northern city of Altamira, killing four people and wounding four others, officials said Sunday.
Security camera footage from the shooting late Saturday showed a crowd of patrons sitting at tables outside the bar when two attackers with handguns approached and shot multiple people, then ran away.
There have been at least 12 murders in Altamira in less than two weeks, including the latest shootings, according to local media reports.
Authorities said they were investigating whether the crimes were related.
Barbalho, who traveled to the city of 117,000 people Sunday, said he had launched a 50-officer task force to investigate.
Para state has been the scene of bloody turf wars in the past between rival drug gangs and mafia-like militia groups.