Police say when they arrived at Dotcom's property at 6:45am, at first Dotcom's bodyguards would not let them in. There were 15 people at the house at the time, including employees and family members.
Two shotguns were found on the property, police are looking into whether these are restricted weapons in New Zealand.
All those arrested this morning will appear in the North Shore District Court this afternoon.
Police have also seized luxury cars with an estimated total value of up to $6m.
These include a Rolls Royce Phantom Drophead Coupe valued at over NZ$500,000. Over $10m has also been seized from NZ financial institutions, including New Zealand government bonds.
Dotcom lives at the Chrisco mansion in Coatesville, north of Auckland, which he rents.
His application to buy it was declined by the Overseas Investment Office last year, according to the
National Business Review. His application was initially approved, but then denied after then Associate Finance Minister Simon Power and Land Information Minister Maurice Williamson decided he did not meet the 'good character' test, according to the
New Zealand Herald.
His application for residency was approved after he invested $10 million in government bonds and made a donation to the Christchurch earthquake fund, despite admitting two convictions – one for hacking, and another for insider trading.
Dotcom says the convictions were wiped under a German "clean slate" law.
"Officially I am as clean as it gets," he said last year.
"I am not a bad person with a bad character and, in my opinion, Simon Power is small minded and unreasonable.
"In New Zealand, murderers have been released from prison within a decade. You would think that the New Zealand Government believes in giving people a second chance."
Many New Zealand-based Twitter users this morning have been questioning whether agreements between the US and New Zealand allows extradition for copyright infringement.
Left-wing blogger
Idiot/Savant tweeted: "copyright infringement is not an extraditeable (sic) offence according to the NZ-US treaty".
But legal blogger tweeted
Graeme Edgeler said "people can be extradited from NZ to US for ANY offence that in both countries carries a penalty of at least 12 months' imprisonment".