A gun attack on a crowd of birthday party revellers that left four people injured, one seriously, could have resulted in numerous fatalities, gardai have said.
Detectives said the gunman who fired at a crowd outside a north Dublin bar in the early hours was "indiscriminate".
The gangland style attack happened in front of Hanlon's pub on the Old Cabra Road at around 2.30am. The area is one of the city's popular night-time destinations.
A 28-year-old man sustained serious injuries in the attack and three women - aged 19, 28 and 33 - were also shot.
It is understood the women were shot in the legs. Their injuries have been described as not life-threatening.
The injured man was said to be in a serious condition in the Mater Hospital.
Garda Superintendent David Taylor appealed for witnesses to come forward.
"It was an indiscriminate shooting of people enjoying themselves out at a 21st party," he said.
"The consequences are very serious. The consequences could have been absolutely awful."
The officer added: "We are calling on anybody who may have any information in relation to this shooting to come forward and assist us."
Gardai particularly want information as to the whereabouts of a car seen driving off at speed from the scene of the shooting.
No arrests have been made so far. The area has been sealed off for forensic examination.
Government minister Joe Costello, who is a TD for Dublin Central, said the shooting had shocked the local community.
"I live in the neighbourhood and I know that such acts of violence are totally uncharacteristic of the area," he said.
"The indiscriminate nature of the shooting highlights the murderous intentions of the culprits. That a 21st birthday party should end in such a brutal fashion is unacceptable in a civilised society.
"Gardai must ensure that the perpetrators of this terrible crime are brought to justice quickly and that the local community is reassured that the Gardai are in control of policing in the area."