Two men were shot dead when a gunman burst into a Dublin inner-city flat last night and opened fire.
Both victims were aged 50 and shot in the head and body.
Gardai believe one of the victims was an innocent bystander and the other was the target of the shooting, which officers believe was linked to a gangland murder on the west side of the city in June 2008.
The shootings, which bring to three the number of murders so far this year, took place in the flat at Pearse House, Pearse Street, in Dublin's south inner city, shortly before 7pm.
The victims were named last night as Brendan Molyneaux, who had an address in a hostel in York Street, and Paddy Mooney, who lived in the apartment. Three men and a woman were arrested in Finglas last night over the shootings.
Gardai believe Molyneaux had been targeted by those responsible for the murder of armed robber Paul 'Farmer' Martin, who was shot in the head and stomach in the Jolly Toper pub at Church Street in Finglas, as he mingled with mourners after a funeral.
Martin (30), a well known criminal since his teens, was shot shortly after he clashed with a major underworld figure, who is regarded as the current boss of the drug trafficking gang formerly led by Martin 'Marlo' Hyland.
The suspect joined forces with other leading criminals to take over the remnants of the gang after Hyland had been shot dead in Finglas by his associates.
The suspect is also believed to have placed a €30,000 "contract" on John Paul Joyce, whose body was found in a ditch at the back of Dublin Airport on Saturday afternoon.
Joyce, who was released from prison in November, had been under threat since then.
Gardai believe he was abducted in Coolock on Thursday night, bundled into a vehicle, taken to Dunbro Lane, at the rear of the airport, shot and dumped in the ditch.
Two of the suspect's close associates, both originally from Finglas, are thought by detectives to have been behind last night's double murder.
Fire brigade ambulance personnel rushed Mr Molyneaux and Mr Mooney to St Vincent's Hospital.
But Mr Mooney was pronounced dead shortly after he was admitted and Mr Molyneaux died from his wounds an hour later.
The area around the flat was sealed off last night pending the arrival of technical bureau experts while detectives from Pearse Street began inquiries into the complex.
A third person may have also been in the flat when the gunman struck but was not injured.
Gardai said initial details of the attack were unclear and they were interviewing people in the area.
A post-mortem examination on the two bodies will be held later today.
Officers were satisfied last night that Mr Mooney had no gangland connections and was unlucky to have been "in the wrong place at the wrong time".
They suspect that the Finglas drugs gang singled out Mr Molyneaux because they thought he might have been involved with a group planning to target them as a result of the Farmer Martin shooting.
Martin, who was originally from the Cardiffsbridge Road area of Finglas but had lived at several addresses in the district, had a dozen criminal convictions including a five-year jail sentence for an armed hold-up at a bank in Ardee, Co Louth, in November 1997.