A leaked draft report obtained exclusively by Lateline has for the first time outlined what happened during the Good Friday rampage at the Manus Island detention centre, culminating in claims gunshots were fired into the facility.

Key points: The report provides a detailed timeline of the four-hour-long confrontation

The report provides a detailed timeline of the four-hour-long confrontation "This is confirmation that bullets were fired into the detention centre," Senator Nick McKim says

"This is confirmation that bullets were fired into the detention centre," Senator Nick McKim says Document confirms reports trouble began when asylum seekers were playing soccer on nearby field

The document, understood to have been written by a member of Wilson Security, said an M16 assault rifle and a shotgun were used in the clash between members of the Papua New Guinea Navy and staff and residents at the detention centre.

The report titled "Debrief Points - Critical Incident 14th April 2017", is riddled with spelling and grammatical errors but provides a detailed timeline of the four-hour-long confrontation.

"A member of the PNGDF produce [sic] a weapon, believed to be an M16 Assault Rifle, and proceeded to discharge his weapon randomly into the air and towards the RPC, Staff and facilities," the report said.

Greens senator Nick McKim recently visited Manus Island and was denied entry to the detention centre but he did manage to meet with asylum seekers in a nearby town. He backs the Wilson document's findings.

"This is confirmation that bullets were fired into the detention centre," Senator McKim said.

"That's no surprise to me because I've actually held one of the bullets that ended up on the floor of one of the sleeping areas inside the Manus Island camp."

Timeline of confrontation

The document confirms reports the trouble began when asylum seekers, referred to as residents, were playing soccer on a nearby field.

The Manus Regional Processing Centre is located within the PNG Naval base.

Local children wanted to use the soccer pitch — but "using profanities" the residents "told them to go away".

The father of one of the children, a PNG Navy officer, approached the residents and told them to leave, but they refused and, according to the report, "commenced assaulting the Navy member. This caused other Navy personnel to come to his assistance".

'Rocks and punches thrown'

Fighting escalated, rocks and punches were thrown and the residents fled to the Regional Processing Centre.

The report said two groups of Navy personnel then gathered outside a gate to the detention centre — those involved in the soccer pitch dispute and a second group.

"Members in Group 2 returned and armed with lengths of bamboo and other assorted weapons and commenced assaulting staff and a member from PNGICSA [PNG Immigration and Citizenship Service Authority]," the report said.

"… a number of Wilson Security staff had been injured."

Lateline understands several of the injured staff were Australian citizens.

"Security staff had to withdraw back along Route PUGWASH as Navy Personnel continued to try and assault them and also drive a vehicle into Gate 22 in an attempt to gain access," the report said.

Staff told to find cover

Sorry, this video has expired Video from the Refugee Action Coalition allegedly captures gunshots being fired into Manus Island detention centre

According to the report, at the detention facility's security control room, security staff watched on CCTV as several men pulled out firearms and started shooting.

"The Navy Personnel were still angry and produces [sic] firearms and commenced discharging them. These were believed to be one by M16 Assault Rifle and one by shotgun," the report said.

Some staff members came out of buildings to investigate before all were yelled at and told to move and find cover.

That moment seems to have been captured in mobile phone footage published online by the Refugee Action Coalition.

Eventually, with several security staff in need of medical assistance and many more fearing for their lives, the mob dispersed.

'A building situation'

A recent report from Amnesty International also said guns were fired directly into the facility, not just "into the air" as claimed by the Department of Immigration and Border Protection.

In the wake of the incident, Immigration Minister Peter Dutton said tensions had risen on the island because of allegations surrounding asylum seekers and a young local boy.

"There was an alleged incident where three asylum seekers were alleged to be leading a local five-year-old boy back toward the facility and there was a lot of angst around that, if you like, within the local PNG community," Mr Dutton said.

"I think some of the local residents were quite angry about this particular incident and another alleged sexual assault."

The leaked report contains no reference to the alleged incident involving the five-year-old. Its summary concluded:

"It was an incident that had not been thought of or talked about. It was in hindsight an incident that escalated to almost worse [sic] possible case scenario and could be looked at as the end state to a building situation we all knew about but did not see coming. To predict what was going to happen that afternoon was impossible, but again should have been something that should have been discussed as a possible outcome of recent events."

The report does not detail what those recent events were, nor does it explain the context of the so-called "building situation" but it could relate to two separate arrests earlier this year.

One a 28-year-old Pakistani refugee — charged in March over the alleged sexual assault of a 10-year-old girl — and another asylum seeker charged in January for allegedly assaulting a 19-year-old student.

Two investigations are underway into the Good Friday incident, one by PNG Police and another by PNG Defence.

An official from Wilsons Security, who did not want to be named, told Lateline the leaked document seemed in line with normal debriefing protocols.

Lateline approached Mr Dutton's office but no comment was provided.