Two people have already been before the Masterton District Court, while the other is expected to appear next week.
Police warned six other people for drug offending.
Detective Corey Reid said he hoped these arrests would send a strong message that offenders would be held accountable for causing harm to communities.
“This latest operation was a part of the proactive action being taken with Operation Cobalt, targeting illegal activity by gang members and their associates.”
Reid said there would be a “highly visible” police presence ahead of Christmas, and the community “can be reassured by this”.
Police said anyone with information should contact 105 or Crime Stoppers anonymously on 0800 555 111.
“Our message to gang members who want to continue to victimise our communities with drugs, violence and firearms, is that we will be targeting you,” Reid said.