A mother-of-six and a man have been shot dead in a gun attack linked to a long-running feud.
The woman, aged in her 40s, was shot dead along with the man, who was aged in his 30s, at a house in an estate in the Ballymun area of north Dublin.
Another woman and man were injured.
It is understood that one of the intended targets of the shooting escaped.
Gardai said one gun and two partially burned-out cars were recovered in the hours after the killings.
The killers struck shortly after 4pm on Balbutcher Drive, a residential area in the Poppintree end of Ballymun.
The victims were gunned down at the front of a family home and th ere were several people in the property at the time.
It is understood one young woman was injured when the gunmen opened fire while she was holding a young child. The youngster is believed to have suffered only minor injuries.
The woman was treated in the Mater Hospital along with the injured man.
Detectives appealed for anyone who was in the area during the day and noticed anything suspicious to come forward.
They also urged anyone who may have dashcam footage from cameras or phones in cars to make contact with them in Ballymun station, including taxi drivers or delivery workers.
Gardai said a silver Opel Zafira with 08 LS registration plates was found partially burned-out a short distance from the scene of the shooting.
A short time later, a Volkwagen Golf GTI with 06 LH 3466 registration plates was found on Santry Close.
The area was sealed off with Garda scenes of crime officers expected to carry out forensic examinations and scores of gardai from specialist and detective units, including armed officers, on the street.
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 dead women and another man who was targeted in the gun attack is the brother of a man shot dead in Dublin in early 2014.
Politicians roundly condemned the incident.
Justice Minister Charlie Flanagan said the murders were outrageous.
"These ruthless people have no regard for human life and this will not be tolerated," he said.
"The gardai continue to confront this threat daily and are determined to see those involved brought to justice.
"This callous, cold-blooded violence has no place in our communities - the Government and gardai stand with the people of Ballymun against such despicable acts."
Mr Flanagan vowed to maintain high-visibility policing to combat gun attacks, including extensive armed checkpoints across Dublin.
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.