A Dublin taxi driver was shot dead on Monday night, local media reported, as fears grew of escalating gang violence in the Irish capital.
Eddie Hutch, 59, died after gunmen burst into his home in the north of the city.
The Irish Independent newspaper reported the attack was retaliation for the killing of David Byrne at a boxing match weigh-in at a Dublin hotel on Friday.
Justice Minister Frances Fitzgerald said it was “another deplorable example of the ruthlessness of gangland criminals”, the Independent said.
Fitzgerald added: “It seems that some gangs are intent on waging a feud where human life counts for nothing.”
The rise in violence comes in the second week of Ireland’s parliamentary election campaign.
Claims that the successive shootings are the result of tensions between rival elements connected to the Irish Republican Army (IRA) have been dismissed by Sinn Fein, the political party historically associated with the militant group.
Responsibility for Friday’s shooting was claimed by the Continuity IRA, an IRA splinter group, in a statement to the BBC but was contradicted a later statement to the British broadcaster.