Four people were being questioned today after gardaí seized a handgun and €4,200 worth of heroin from a house.
Two bullet-proof vests and other drug paraphernalia were also discovered during the raid in Grange View Road in Clondalkin, south-west Dublin, at 9pm last night.
Three men aged 20, 23 and 24 and a woman aged 26 were arrested and taken to Clondalkin Garda station.
They can be held for up to seven days under section 30 of the Offences Against the State Act.
The search was carried out by officers from Clondalkin Drugs Unit, the District Detective Unit and Operation Anvil, an ongoing operation to tackle gun and drug-related crime in the capital.