The Armed Offenders Squad and a team of armed uniformed police searched an industrial area of Gate Pa yesterday.
Police remained tight-lipped last night other than saying they were executing a search warrant in relation to an ongoing inquiry.
Acting area commander Inspector Karl Wright-St Clair said he had spoken to the officer in charge and no comment would be made about the investigation at this time.
Witness Mitchell Robinson, who works two buildings away, said he saw six armed policemen in Wilrose Place, off Courtney Rd in Merivale, yelling for a person to exit a building with their hands up.
Several other policemen were also seen in and around a business at the end of Wilrose Place.