More than 300 police officers carried out raids on a major drug trafficking network in the Montreal area this morning.

Laval police say they seized hundreds of thousands of dollars in cash and tens of thousands of synthetic drug tablets.

Sgt. Frédéric Jean with the Laval police said one of the biggest stashes was found in the Laurentians, where pills were being manufactured.

“The transformation point that is in Saint-Lin-Laurentides has quite a large amount of bulk synthetic drugs there. The drugs were in a powder form and being pressed into a tablet form,” said Jean.

The operation began at 5 a.m., involving 36 warrants in seven cities including Montreal, Laval and the North and South shores.

Police have made at least 27 arrests.

Jean said the investigation called "Projet Souterrain" — or "Project Underground" — is being led by the Laval police’s anti-gang unit.

He said it started with an anonymous tip in September 2013.

“We're looking at breaking up an operation that deals with the distribution and trafficking of synthetic drugs, cocaine and cannabis,” said Jean.

Jean said the trafficking network covers a vast territory that extends from St-Bruno and Candiac on the South Shore, to Blainville and Saint-Jérôme on the North Shore.

The raids involved officers from eight different organizations including Laval Police, the Sureté du Québec and the RCMP.