Durham police have busted a major drug-smuggling ring operating out of the Dominican Republic, seizing more than $3 million worth of cocaine in a series of pre-dawn raids.

Twelve people were arrested in various southern Ontario locations, including the GTA and Barrie, Ont., early Tuesday morning.

A dozen firearms, including assault riffles, and an estimated $445,000 in cash were also seized.

Police say the bust has shut down a smuggling ring that was operating through Pearson International Airport from the Dominican Republic.

"We've dismantled a significant cocaine pipeline in the GTA that involved hiding drugs in cargo planes from the Dominican Republic, landing at Pearson Airport," Durham Police Chief Mike Ewles said during a press conference.

"This cocaine would have made its way onto the streets of the GTA and across our province."

More than 200 charges have been laid against the suspects who include a baggage handler at the airport and a member of the Hells' Angels motorcycle gang from Oshawa, Ont.

The raid involved more than 220 police officers from various jurisdictions.