A notorious terror boss known as 'The Beast' was murdered when he was ambushed and shot in the back at least three times.
Gardai fear dissident Republican reprisal attacks after the victim, Aidan O'Driscoll, was gunned down.
The 37-year-old Real IRA commander died during emergency surgery an hour after being targeted in Blackpool, Cork.
O'Driscoll is suspected of serving as chief of staff for the Real IRA in Munster and had close links to murdered Real IRA boss Alan Ryan from Dublin.
The attack took place shortly before 5pm and is understood to have involved a lone gunman and a getaway driver.
Locals reported hearing several loud bangs and seeing a man, apparently masked, running from the scene.
He is believed to have fled the area in a getaway car driven by another masked man.
Initial reports suggest O'Driscoll realised he was being ambushed and attempted to flee.
He was shot in the back with a 9mm handgun and collapsed to the ground. The gunman then walked up to him and shot him a number of times as he lay wounded on the pavement.
A short time later, a burning car was found less than a kilometre away. A second car was found burnt out in the village of Killeen, outside Cork city.
O'Driscoll was treated at the scene by paramedics before being rushed to Cork University Hospital (CUH). It is understood he was shot in the back at least three times.
O'Driscoll had survived a gun attack three years ago, when he was shot in the legs in what gardai believe was a punishment operation carried out by fellow dissident Republicans.
O'Driscoll was convicted before the Special Criminal Court in 2005 of being a member of the Real IRA and received a three-year prison sentence.
His conviction was overturned on appeal and O'Driscoll moved to Dublin in the latter part of the last decade.
O'Driscoll had been closely allied to Alan Ryan, the leader of the Real IRA at the time, who was shot and killed in 2012.
While in Portlaoise Prison, he shared a landing with Ryan, who was himself serving a sentence for weapons offences.
Upon his release, he assumed command of the Real IRA in the capital and both he and Ryan waged war on drug dealers flooding the country and making huge money.
They claimed in interviews that they were taking the drug dealers' money and weapons and running them out of communities.
However, senior sources say the Real IRA was simply demanding large sums of cash from criminal gangs and, if they refused to pay up, they became targets for the feared dissident gang who traded under the IRA name.
The group was responsible for the murder of Colm 'Collie' Owens in July 2010.
O'Driscoll also sanctioned the murder of drug-dealer Sean Winters, who was shot twice in the head outside an apartment in Portmarnock in September 2010.
O'Driscoll ordered the murder of Gerard 'Topper' Staunton, who was gunned down in Cork in an ambush-style killing in January 2010.
A year later the Real IRA had major Dublin drugs trafficker Michael 'Micka' Kelly killed.
O'Driscoll was shot outside an apartment complex off Blackpool village in Cork.
Detectives are checking CCTV security cameras to see if the attackers were caught on film.