Police there stopped a vehicle along the 100 block of 9th Street East on Friday.
Owen Sound Police along with the Criminal Investigations Branch arrested a 44-year-old man from Owen Sound.
Three more were arrested at a home in the city after a search warrant was executed there.
Officers seized 159 grams of methamphetamine, 69 grams of cocaine, 31 hydromorphone pills, plus a bolt action rifle, an assortment of imitation firearms and BB guns, and around $2,500 worth of stolen tools and property.
They say the total value of the drugs seized is around $68,000, and the amount of the seized fentanyl represents over 1,500 lethal doses.
All four are facing charges and are being held for bail hearings.