UPDATE 8pm: A mother-of-six and a man have been shot dead in a gangland style shooting in Ballymun.
It is understood the target of the shooting escaped and that there was a child in the house when the gunmen struck. The child was slightly injured, while two others - a man and a woman - are being treated in hospital. Their injuries are not life-threatening.
The killings are believed to be part of a long-running feud in the area, which has seen a number of shooting and assaults.
It is understood the target of the latest attack is the brother of a man shot dead in Dublin in early 2014.
Gardaí are examining a firearm they recovered. They would not say how many gunmen they believe were involved.
Meanwhile, a second car is being examined in relation to the attack - Golf GTI, registration 06 LH 3466.
Politicians roundly condemned the incident.
Minister for Justice Charlie Flanagan said: "This outrageous attack is totally unacceptable...I utterly deplore this shooting which has tragically resulted in the loss of two lives as well as others injured.
"This callous, cold-blooded violence has no place in our communities - the Government and Gardaí stand with the people of Ballymun against such despicable acts and will continue to ensure there is high visibility policing to combat such attacks, including extensive armed checkpoints across the city, for as long as necessary."
Roisin Shortall, local Social Democrat TD, said there had been recent tensions in the area and that the community feared an escalation of violence.
"The horrific incident is a chilling reminder of the extent of gangland crime on Dublin's streets, much of it drug fuelled," she said.
"The incident should act as a wake-up call to the Government that gangland crime in Dublin remains prevalent and wreaks havoc across the city and in many local communities.
"It is crucial to invest in adequate policing and it is also crucial to invest in and to sustain investment in building safe and strong communities across the city."
Dessie Ellis, Sinn Fein TD for Dublin North West, said: "We have to ask people to desist.
"Nobody should be targeted, nobody should retaliate or get involved.
"I'm asking people not to get involved or caught up in these personal disputes. No one losing their life is worth it."
Mr Ellis also questioned the level of Garda resources in the area.
EARLIER: Gardaí said the victims, a woman in her 40s and a man in his 30s, were gunned down on a housing estate in the Ballymun area of north Dublin.
The attack took place shortly after 4pm.
Another man and woman were also injured in the incident. They rushed to the Mater Hospital where they were understood to have non life-threatening injuries.
The shooting occurred on Balbutcher Drive in the Poppintree area.
Gardai said a silver Opel Zafira with 08 LS registration plates was found partially burnt out a short distance from the scene of the shooting.
The area was sealed off with Garda scenes of crime officers expected to carry out forensic examinations.
Officers appealed for anyone who was in the Balbutcher Drive area this afternoon between 3pm and 4pm to contact gardaí in Ballymun Station on 01 666 4400