A police witness has described hearing gunshots and military-style commands coming from the Urewera area where the crown says training camps were being held.

The officer, who has name suppression, was giving evidence at the trial in the High Court in Auckland of four people accused over the alleged camps.

Tame Iti, Te Rangiwhiria Kemara, Emily Bailey and Urs Signer are on trial in the High Court in Auckland facing charges of participating in an organised criminal group and firearms charges.

The officer with name suppression described hearing semi-automatic weapons and a gun with a silencer being fired, along with military commands being issued.

"You could hear someone yelling out for instance `bang bang bang bang', simulating firing weapon at one stage, commands like `fall out, fall out', `go, go, go, go'," the witness said on Wednesday.

Earlier police witnesses were questioned about the installation of surveillance cameras and about tracking the accused.

Senior Sergeant Mike Horsnell described tracking Kemara on a variety of journeys from Auckland to Bay of Plenty between 2006 and 2007.

He also gave evidence of texts allegedly sent by Iti to various other people, including one warning that "there are many eyes watching".

But when asked by Iti's lawyer Russell Fairbrother how he knew Iti sent the texts, he said it was information passed on to him by other people.

Earlier, Detective Inspector Geoff Jago told Mr Fairbrother he hadn't familiarised himself with the history of Tuhoe's grievance and activism which had been heard by the Waitangi Tribunal.

The cameras were placed on the confiscation line which marks the Crown's hotly-disputed seizure of Tuhoe land in the 1860s, but Det Insp Jago said there was no conscious decision to place the camera on the confiscation line.