At least 26 combatants and an unconfirmed number of bystanders were killed in a gunbattle between warring tribes in Papua New Guinea, police said on Monday.

A tribe, their allies and mercenaries were on their way to attack a neighbouring tribe when they were ambushed on Sunday in Enga province in the South Pacific nation’s remote highlands, Royal Papua New Guinea Constabulary acting superintendent George Kakas said. Police commissioner David Manning later described the clash as a “gunbattle between warring tribes”. An unconfirmed number of villagers also were killed. Police reinforcements were sent to the scene of the battle, Manning said.

“At this point, it’s not clear exactly how far we have moved into the conflict there,” Manning said. “But the intent is to regain control or have a significant presence in that conflict area and then work...our way through our procedures in dealing with this type of incident.”