The seven Australians, one New Zealander and at least four Papua New Guinea porters, who were helping the tourists, had set up camp Tuesday along the popular Black Cat Track hiking trail in Papua New Guinea's northern Morobe province when the attack took place, Australian Broadcasting Corp. reported Wednesday.
Two of the porters were killed and the other porters and four of the hikers were badly injured, Papua New Guinea police spokesman Dominic Kakas said.
"One of the expatriates was speared through the left leg, one was slashed on the arm, another suffered severe lacerations to the head and another also had severe cuts," he said.
"There were six in the mob that attacked them," he added, saying that all the attackers had escaped. "One had a rifle, another a home-made gun, as well as bush knives and spears."
Papua New Guinea Prime Minister Peter O'Neill said the attack was an "obvious setback" to the nation's attempt to clean up crime and increase tourism.
"I make no apology whatsoever for the death penalty being the punishment available to be applied for such crimes," he said.