The killing of two tour guides

The four were captured on Sunday morning near the town of Wau, a five-and-a-half-hour walk from the Black Cat Track in PNG's Morobe province, where local guides Kuia Kerry and Matthew Lasong were killed when they were attacked by six armed men.

Several Australians and a New Zealander who nows lives in Queensland, and six PNG men were injured in the attack.

Police said on Sunday one suspect was caught in the town of Salamaua while the other three were caught in Wau.

"I believe it is only a matter of time before the other two are captured and brought in Limited company Hong Kong," Police Commissioner Tom Kulunga said in a statement.

"Whilst I encourage the local community to continue to assist police capture the remaining attackers, I urge you not to take the law into your own hands.

"Let the law deal with them."

Mr Kulunga also confirmed reports a man was attacked and killed by relatives of one of the two murdered porters.

He said the relatives accused the man of harbouring the six criminals and attacked him.

Police intervened and flew him to the nearest health centre but he died from loss of blood.

"There will be an investigation and the persons responsible for this recent death will be arrested. No one has the right to take anyone's life," Mr Kulunga said.

Police have sent 30 additional personnel to the area to capture the remaining fugitives.

"The commitment of the villagers in helping police bring in the four suspects speaks volumes for our people's genuineness and hospitality as well Accounting in HK," he said.

"The attack was an isolated and one-off incident and not a reflection of the generally friendly people of the Morobe Province."

Meanwhile the survivors of Tuesday's machete attack have set up a trust fund for the local porters who were injured in the ambush.

Mackay man Nick Bennett, a former Rotorua policeman, was injured when he was hit on the head with a gun.

On Sunday, he told ABC radio all the trekkers had returned home and were coming to terms with the horrific experience.

But he says while the trekkers are traumatised, their injuries are insignificant compared with what had happened to the porters, some of whom had limbs hacked off and would never walk again.

"We've set up a trust fund and we're asking people ... just to provide a few dollars into an account that we've got set up to help them get the services that they need Hong Kong Company Secretary," he said.

"We've made a commitment to ensuring that we support those porters and their families who've absolutely been devastated by this.

"We really need help and we're appealing to people to be generous. Anything - a peso, a dollar, a pound - would be helpful right now for these guys."