Durham police say officers executed 22 search warrants — including 16 in Durham Region, two in Toronto and two in York Region — following a four-month investigation called Project Bermuda.
The other raids were in Bancroft, northeast of Peterborough, and the Kawartha Lakes area.
Police say drugs including cocaine, hashish and marijuana were seized, along with $100,000 in cash, weapons and vehicles.
Durham police say the investigation began earlier this year after weapons and drugs were found at a home in Oshawa.
The probe grew to involve 11 other law enforcement agencies and targeted street-level drug sellers in the region.