A garda helicopter is this evening leading a search of north Dublin following the arrest of a gunman on a motorbike on Richmond Road.
A second man, who was on the bike, had escaped,Gardai are still searching for him.
The drama began at about 3:30pm when gardai spotted two men acting suspiciously on a motorbike in the Richmond area.
Gardai chased the bike and after a short time apprehended one of the men.
They recovered a loaded pistol and seized the motorcycle. The second motorcyclist managed to escape.
The garda helicopter was immediately called out and has been leading a search of the area.
The arrested man, who is 20, is being held at Whitehall garda station under section 30 of the offences against the state act and can be held up to 72 hours before being charged or released.