A Papua New Guinea activist has described the actions of police who opened fire on a group of university students as an ambush.
"They were assaulting and firing at them," People's Power Movement leader Noel Anjo said.
Mr Anjo also rejected reports the students were preparing to march on the nation's parliament, amid mounting civil unrest revolving around serious corruption allegations aimed at Prime Minister Peter O'Neill.
The students were about to board buses to take them to the parliament to present a petition.
"There was no march," Mr Anjo, who was part of the student organising team, told ABC television on Thursday.
"There were flags and maybe one or two banners, they were in the bus.
"The police ordered them to move out of the bus, pulled them down and then they said `you're not going to Parliament' and then it was like ambush."
The PNG government says five students were wounded - other sources put the number as high as 15 - in the clash and denies anyone was killed by the officers.
The Australian government says it can't confirm earlier reports up to four people had died.
Mr Anjo said the "police started everything".
"We're mourning, we're mourning for our country because our country is sinking," he added.
University of Papua New Guinea student representatives are expected to meet on Thursday to decide how to respond to a PNG court injunction sought by the institution that bars students from protesting on campus.
The PNG government has backed the injunction and blamed Wednesday's violence on student "thuggery".
Foreign Affairs Minister Julie Bishop has made repeated calls for calm in PNG and says Australia remains concerned about the incident in Port Moresby.
"We want the tensions to de-escalate but it is still a volatile situation," she told reporters in Sydney.
Political unrest is sweeping PNG as Mr O'Neill faces continual calls for him to resign as prime minister.
He's refusing and describes the corruption allegations as being "of questionable political intent".
The allegations relate to financial mismanagement off the back of a long-running corruption investigation.
"We are fed up with the government, we are fed up with the police," Mr Anjo said.
Prime Minister Malcolm Turnbull has offered assistance to the PNG government to help prevent further unrest but its yet to be accepted.
Australians in PNG are being warned to be extra vigilant.
