A man in his 20s is still being questioned in connection with the seizure of drugs and ammunition in Blessington, Co Wicklow.
Gardaí returned to the outskirts of Blessington earlier today to conduct further searches in the area.
Heroin with a potential street value of €750,000 was seized during a planned operation last night.
It is believed the location was that of a city criminal gang's rural drugs and firearms hiding place
Gardaí from Baltinglass backed up by the ERU arrested the man, who is in his late 20s, and from Ronanstown in north Dublin. It is understood he is a target of the Garda National Drugs Unit.
He is being held at Naas Garda Station and can be held for questioning for up to a week.
Gardaí recovered 3kg of heroin worth, a Glock semi-automatic pistol and more than 50 rounds of ammunition.
The gun will be forensically examined to see if it has been used in any shootings or murders.
This is the second significant drugs and firearms discovery in a 24-hour period this weekend.
Meanwhile, a man is due to appear before Blanchardstown District Court in connection with the seizure of drugs at a house in Clonne, Co Meath yesterday.
Gardaí in Blanchardstown seized a quantity of what is believed to be cocaine and cannabis plants.
The 38-year-old man is due in court on 16 December.
