A series of police raids across the city netted drugs, guns, and enough chemicals to produce 600,000 counterfeit pills, Ottawa Police said on Wednesday.

The raids, which happened Tuesday after an eight-month investigation by the Ottawa Police Drug Unit, targeted eight homes, businesses and vehicles across the city.

Four people from Ottawa were arrested and charged, and police say two others - men aged 32 and 27 - remain at large.

The investigation uncovered a pill press capable of producing 20,000 pills per hour, police said. Along with the chemicals, police found an assortment of drugs including cocaine, ecstasy, MDMA and marijuana. They also seized a sawed-off shotgun and a handgun with 400 rounds of ammunition.

Two cars, cell phones, computers, and cash were also seized.

"This is an important seizure that shows the ability of traffickers to produce large amounts of counterfeit pills locally," Staff Sgt. Rick Carey said in a release. "It also shows the link between drug traffickers and the potential for gun violence in Ottawa."

Carey said police are focusing on enforcement to prevent drug overdoses, "especially as we begin the music festival season where access to illegal drugs like ecstasy and other counterfeit pills is a major concern."

Brian Nguyen, 28, was arrested and charged with two dozen offences, mostly drug and gun-related. He's being held pending a bail hearing.

Allison Hayes, 27, is facing eight charges. Calvin Tan, 24, is facing six charges. Nabil Zazy, 24, was charged with conspiracy. All were released on a promise to appear.