The police operation focused on two adjacent homes and a third across the street. One car was towed away and police were seen searching homes, garages and vehicles.
Men dressed in Mongrel Mob sweatshirts were marched out of a house next to Simson Park and photographed before being made to remove their gang regalia, which was sealed in evidence bags and taken away.
One man, aged 17, was taken away in handcuffs by police. As he was led to the car he howled like a dog in a Mongrel Mob salute. The SPCA collected a real dog from another house.
Detective Inspector Kevin Burke, of Northland police, said three men were arrested - aged 17, 32 and 58 - and charged with drug-dealing, assault and burglary offences. They are expected to appear in the Kaikohe District Court today.
The total amount of P, or methamphetamine, seized was not yet known but it was more than 5g, enough to satisfy the presumption of dealing. None of the charges were related to the death of Mr Rata.
However, Mr Burke said police believed members and associates of the Mongrel Mob were involved in the assault, and that gang members from Moerewa were present at the wedding and reception that took place at Bonnett Rd. Police were continuing to identify people who were at the function.
"We are locating them and talking to them about what they saw and how they may be able to assist the investigation. We have obtained a large number of images from the party, allowing us to identify who was present. We believe that included some gang members from Moerewa."
Mr Burke said police were still trying to establish how many people were present during the "vicious beating" of Mr Rata and how many were actively involved. The investigation would continue until all those responsible were located.
Officers from Northland, Waitemata, Counties Manukau and Waikato were working on the investigation.
Police were also still trying to establish whether Mr Rata had links to the gang, he said.
Mr Rata's Facebook page, however, lists his occupation as "Mongrel Mob at Gang member". The father of two lived in Kaitaia but was originally from Matangirau, near Kaeo.
One theory being put forward for the attack is that it was related to tensions between Mongrel Mob factions.
Leatty St residents gathered at their gates yesterday to watch the goings-on. One young woman said she was related to Mr Rata - she described him as a humble man who kept to himself - and was shocked that people in her neighbourhood could be involved in his death.
A 22-year-old Northland man has so far been charged with murder. He appeared in the High Court at Whangarei on Tuesday. He was remanded in custody and granted interim name suppression.
- Anyone who was at the party but has not yet spoken to police, or who has information about Mr Rata's death, is urged to call Kaitaia police on (09) 408 6500 or Crimestoppers, anonymously, on 0800 555 111.
