Police cars and vans have been seen in and about the town, with officers also targeting back roads.
Cordons are on Marokopa and Mangatoa roads - the only way in and out of the town that does not even have its own local police station.
Police are casting a wide net, and some cordons are set up 15km apart.
One of the cordons was backed by a farm and dense bush. Police said getting into the bush was posing challenges.
The Eagle helicopter was called in on Wednesday.
"Police believe they're somewhere in this area," RNZ reporter Maia Ingoe said from Marokopa.
There were fewer than 100 homes, and residents were keeping to themselves, she said.
One local said the extra police presence and the media attention on Marokopa was a "nuisance". He did not want any more visitors to the area.
Phillips and the three children have been missing for two and a-half years.
Police arrived on Wednesday after issuing an $80,000 reward for information that could lead them to the children, now aged 8, 9 and 10.
Officers have set up four cordons and are checking everyone entering and leaving the community.
Tip-offs about the family have been coming in since the reward was announced on Tuesday but police have not yet revealed how useful it is.
The offer, which includes considering immunity against prosecution for anyone assisting Phillips, lasts for two weeks.
Ember, 8, Maverick, 9, and Jayda, 10, have been missing since December 2021, when they were taken by Phillips to an unknown location - though police believe it was in Western Waikato within Marokopa or the surrounding areas.
The manager of a hotel near Tirau said he had been visited by police about a potential sighting of Phillips and the children.
The New Zealand Herald reported a woman claiming to see Phillips with his children in the thermal pools at the Okoroire Hot Springs Hotel, about two hours' drive from Marokopa, about two weeks ago.
Hotel manager Derek Webb said the police visited the site the night the report was made.
He said he did not see Phillips or his children, nor did his staff.
A Marokopa local said the police presence was almost normal, as they had set up in the area multiple times since Phillips and his children went missing.
Mark Ammon lived across the road from the community centre and rugby field where a makeshift police hub has been set up.
"We're surely used to it, because they're always based at the hall here. They were here for several weeks when Tom Phillips initially went missing, and they've been back two or three times since. Part of the community, now."
One man told RNZ the community were "over it", and another said both the media attention and police presence was a "nuisance".
Ammon said the $80,000 reward was plenty for anyone with information to come forward. But, he said it was hard to say whether anyone knew where Phillips was.
Phillips does not have legal custody of the children. He is sought by police and there is a warrant for his arrest," acting Detective Inspector Andrew Saunders said on Tuesday.
People with information are urged to contact police.
