Gardai stopped a vehicle on the Corbally Road at around 2.15pm yesterday.
€10,000 worth of suspected cocaine was found when they searched it.
Three men aged in their 20s and 40s who were the occupants of the vehicle were arrested at the scene and taken to Henry Street Garda Station, where they were detained under Section 2 of the Criminal Justice Act.
Two of these men have since been released form custody pending files to the DPP.
A number of follow up searches were then conducted in Limerick yesterday evening.
Gardai located more than €400,000 worth of cocaine, €140,000 worth of heroin, €45,000 worth of amphetamine, more than €42,000 of diazepam tablets and a large sum of cash.
A man in his 50s and a woman in her 30s were subsequently arrested and are also detained at Henry Street Garda Station.
Investigations remain ongoing.
