Police, including members of the armed offenders squad and dog section, descended on the Mongols MC's HQ near The Old Sawmill in Burnham, south of Christchurch, about 7am on Monday.
Detective Inspector Julian Rinckes said police carried out a search warrant at the Main South Rd address.
A second search warrant targeting the group was also executed by the Christchurch District Organised Crime Group on Rolleston Drive in Rolleston, Rinckes said.
"The search warrants targeted a core group that are alleged to be involved in the importation, distribution and manufacture of illicit drugs throughout Christchurch.
"While further searches and arrests cannot be ruled out, so far today police have located and recovered about $6000 cash, a stolen vehicle and a loaded semi-automatic .22 calibre firearm.
"Police have arrested one person for breach of bail. The man, aged 45, will appear in Christchurch District Court today.
"As the matter is now before the court, police are not in a position to comment further."
It follows two gang-related incidents earlier this year in which a tattoo parlour and a barbershop in n Christchurch were rammed by vehicles.
The Mongols' Burnham headquarters was also shot at by someone wielding a high calibre rifle around the same time in February. Police raided the property after the incident and found guns, dozens of bullets, $50,000 cash and methamphetamine. Another raid in May revealed drugs, firearms and stolen property.
A police spokesperson said it was too early to comment on the raid and what police were looking for or whether arrests had been made.
