More than a dozen firearms and significant amounts of cannabis and cash have been found in police raids on three properties.
At a Woodville house searched by police on Tuesday, neighbours were surprised to learn hundreds of cannabis plants had been found in a secret underground bunker.
Neighbour Roy Adlington said he saw police in safety masks searching the Grey St property on Tuesday.
Mr Adlington said he didn't know the resident but said the house appeared to be nothing out of the ordinary.
"I knew there was someone in it. They kept it pretty tidy. I thought they might have worked at night and slept during the day."
Another neighbour, who did not want to be identified, said it was a surprise, "but you never Cannabis is found in secret bunker
The firearms, in particular, were concerning.Detective Senior Sergeant Craig Sheridanknow what's going on in other people's places."
Other neighbours, who wanted to remain anonymous, said they knew about the discovery but it was none of their business. "It's [growing cannabis] happening everywhere now days," one woman said.
Police said the Grey St home was searched at 7am on Tuesday, at the same time as police raided another property in Hope St, Woodville.
Detective Senior Sergeant Craig Sheridan, of Palmerston North CIB, said 150 cannabis plants and seedlings were found at Grey St inside an underground concrete bunker, the house and the yard.
"It was very organised, the bunker was very sophisticated, it is very uncommon to find such a thing. Personally I have never come across one before," he said.
At Hope St police said more than a dozen firearms were found, many of them loaded, including pistols, rifles and a shotgun.
"The firearms, in particular, were concerning," Mr Sheridan said. "What was concerning was the quantity of them, that they were loaded and at houses where we considered that there was drug activity."
Hundreds of thousands of dollars in cash was allegedly found at the same property, secreted and buried within the house and grounds.
Police also found a small amount of a substance, believed to be methamphetamine, a small amount of cannabis and some drug utensils, Mr Sheridan said.
Also searched was a property in Pohangina Valley Rd, near Ashhurst, where police found 172 cannabis plants in various stages of growth both inside and outside.
Three people appeared in the Palmerston North District Court on Wednesday afternoon.
Joseph LaHood, 47, was charged with cultivating cannabis, and is due to reappear on April 5.
Jolene Rose, 35, and Sean Murray, 42, faced 14 firearms offences, and were remanded in custody until April 3.