But the members of the Special Tactics Group stopped when they heard weapons being loaded, followed by a volley of shots.
Asked how close, the senior constable said "probably 30 - 40m... It was a volley of shots being fired from a semi-automatic weapon''.
The police officer, who has experience in the Armed Offenders Squad, said it sounded like a "big thumping weapon'' and was possibly a .762 calibre rifle or a .308.
He described hearing a range of weapons, one of which he thought was a gun with a silencer.
The police officer said he heard between 150 and 200 rounds being fired as well as military-style commands
"You could hear someone yell out: 'bang, bang, bang' simulating a firearm. Things like: `Fall out, fall out' and `go, go, go'... We refer to that as contact drills.''
Under cross-examination from Kemara's lawyer, Nick Taylor, the police officer agreed it was hard to say for sure what kind of gun was being fired.
The jurors in the trial today watched more video footage taken by the police during their covert operation.
The footage, captured in January 2007, shows groups of people wearing masks and moving through the bush. Some were carrying guns, others sticks and some were unarmed.
Most of them were wearing backpacks and, at one point, one of them crouched down and used hand signals.
Earlier today, the court heard from Detective Inspector Geoff Jago who was responsible for planting cameras in the bush.
Under cross-examination from Iti's lawyer Russell Fairbrother, Mr Jago initially declined to answer questions about the direction he approached a whare nui and a whare kai and said his answer "could compromise operational methods and numbers involved''.
Mr Fairbrother also asked Mr Jago if he was aware that the Air Training Corps (ATC) and the Territorials carried out military manoeuvres with guns. He then asked if there was any prospect that the ATC would go to war.
Mr Jago responded: "I wouldn't expect school children to go to war, no.''
He was asked if he was aware that one of the police cameras was planted on what is known as the Confiscation Line.
The area has important historical significance to the Tuhoe people because it represents the area of land confiscated by the Crown in the 1860s and 1870s when many Tuhoe people had their crops and homes torched.
He said the police made no ``conscious decision'' to put the camera on the Confiscation Line.
The trial continues.