Wellington police have seized guns and more than $500,000 worth of drugs in raids that resulted in more than 70 arrests.
Detective Senior Sergeant Darrin Thomson said the 73 arrests followed three months of intelligence gathering. More arrests were likely.
More than half those arrested have been charged with drug dealing offences involving cannabis, Ecstasy, LSD and methamphetamine.
Two shotguns, a .22 firearm with a silencer and a stun gun were also seized.
Mr Thomson said police executed search warrants in Wellington, Porirua, Hutt Valley and Wairarapa.
At one property in Upper Hutt, police found 10 cannabis plants over two metres tall and a metre wide.
"This was a sophisticated hydroponics set-up with very good quality plants. We also found 650 tabs of LSD ... at the same place."
Mr Thomson said houses and commercial premises had been used for drug-related activities and it was disturbing to find young children present during some searches.
"Kids aged from 3 to 14 years have been found in environments we believe were detrimental to their wellbeing." He said police had worked with Government agencies to help ensure the safety of the children.
"We've also been concerned at the number of properties searched where people have been redirecting power supplies and effectively stealing it from energy companies to avoid payment and suspicion."