There has been widespread condemnation of the Co Antrim murder of 15-year-old Catholic schoolboy Michael McIveen.
Michael McIlveen
A murder inquiry has been opened by the PSNI, which is treating the attack as sectarian.
Michael McIlveen was attacked on Sunday after being chased from an entertainment complex in Ballymena, Co Antrim.
Four men and a juvenile are being questioned by the PSNI about the murder.
Police chiefs said they are treating the attack as sectarian, and have urged public representatives to help ease tensions and prevent retaliatory attacks.
His family was at his side when he died at Antrim Area Hospital last night.
Extending his condolences to the McIlveen family, Taoiseach Bertie Ahern said the murder was "a shocking reminder of the evils of sectarianism."
He said: "Those responsible for this brutal crime must face the full rigours of the law. They stand condemned in the eyes of all decent people committed to reconciliation and promoting a peaceful society throughout Northern Ireland."
"Determined and visible steps must be taken at all levels to address the type of behaviour which led to Michael's death. I join with others in calling for calm at this time," Mr Ahern added.
Michael was attacked after being chased from an entertainment complex in Ballymena, Co Antrim, just after midnight on Saturday after getting a takeaway pizza.
He was battered by a gang that cornered him in an alleyway and allegedly used a baseball bat before stamping on his head.
SDLP Assembly member Seán Farren said there could be no excuse offered for the attack. "Unfortunately we have witnessed similar attacks in Ballymena and elsewhere in the past, and each one has brought pain and tragedy to the families and friends of those affected," the North Antrim MLA said.
Alliance Party representative Jayne Dunlop branded the murder barbaric and vicious. "He didn't stand a chance," she said. "He was outnumbered by a bunch of cowardly thugs and I hope that the police find and arrest all those involved."
Sinn Féin Assembly member Philip McGuigan claimed that the Catholic community had been demonised in Ballymena for decades. "This murder was unjustifiable and was motivated entirely by sectarian hatred and bigotry," he said.
Sir Desmond Rea, chairman of Northern Ireland's Policing Board, said the attack on Michael McIlveen was vicious and vile.
Local MP and Democratic Unionist Party leader the Rev Ian Paisley has appealed for no reprisal for the murder.
He said: "As we move towards the marching season I would appeal for calm. Any reprisal or upping the ante would serve no purpose other than to make matters worse. I would call on all sides to pull back from the brink before tragedy is multiplied by catastrophe."
Dr Paisley, who has spoken to and prayed with the McIlveen family, added: "This was a horrific attack that will be condemned by all right-thinking and law-abiding people in Ballymena."
He appealed to those with any information to come forward and help police bring to justice those responsible for the "heinous attack".
Northern Ireland Secretary Peter Hain said he was appalled by the killing and urged the public to give police their full assistance.
"Everyone will condemn this murder, which drags Northern Ireland back to the dark days of the past," he added.
The scale of anti-Catholic intimidation, particularly in the predominantly Protestant north Antrim area, caused concern among police chiefs last year.
Catholic families were handed fire blankets in a village on the outskirts of the town last August in an unprecedented move by police attempting to thwart sectarian attacks by loyalist paramilitaries.
Additional reporting: PA
