Key Points:

Further arrests are expected in the wake of a massive drug bust that saw 73 people in custody and more than $500,000 worth of drugs and guns seized.

Detective Senior Sergeant Darrin Thomson, who headed Operation Viper, said the arrests were made over the past eight days and followed three months of intelligence gathering.

He said that more than a dozen other people were still being sought.

More than half of those arrested had been charged with drug dealing offences involving cannabis, ecstasy, LSD and methamphetamine.

Two shotguns, a .22 firearm with silencer and a stun gun were also seized.

The operation targeted major drug dealers and 15 of those arrested were known gang associates, with some instantly recalled to prison, The Dominion Post reported.

Mr Thomson said several first-time offenders had also been caught and charged with drug dealing.

He said he was alarmed they had not come to police attention before now.

The number of children found during the raids were also a concern, he said. Child Youth and Family would be informed in each case.

At one warehouse that was raided, police found a sandpit and a jungle gym set up for a toddler to play on while her father was believed to have worked on his $220,000 drug crop.

The raids hit Wellington city, the Hutt Valley, Kapiti Coast and the Wairarapa.

"This will cause significant disruption amongst the drug community," Mr Thomson said.

Some of the dealers had hi-tech operations, with computer-controlled crops, home safes and complex electrical switchboards - allowing them to steal electricity to run lights, fans and heaters.

Mr Thomson said the drugs would have caused huge amounts of misery, damaging the health of users and putting financial strain on them and their families in funding their habits.

"These dealers don't care what misery they're causing. They just want to make money."

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 Operation Viper had been the most successful operation of its type in the district in the last four years.

"It never ceases to surprise us the extent of the New Zealand drug culture.

"Fifteen of the arrests were associated with gangs but drug offending goes across all levels of society," he said.

Some of the those arrested have appeared in court in Porirua, Wellington, and Hutt Valley and been remanded, while others are yet to appear.