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The outlawed Irish Republican Army apologized Friday for its 1973 killing of a 9-year-old Northern Ireland boy who stumbled across an IRA bomb while playing in his backyard.

The declaration was a major shift, since for decades the group had blamed the boy's death on the British Army, but his father said Friday it was not enough.

The IRA made its admission and apology for killing Gordon Gallagher after the dead boy's parents called publicly for Sinn Fein politician Martin McGuinness, the former IRA commander in Londonderry, to tell them who planted a bomb in their children's play area and why.

The IRA statement said the group accepted responsibility and was "truly remorseful and profoundly sorry." It offered its apologies "for the pain and grief caused."

The IRA has issued similar admissions and apologies over the past 15 years for killings that it long denied committing and sometimes falsely attributed to the British Army. Friday's statement came on the eve of the 39th anniversary of Gordon's death.

His parents say Gordon was running around their back yard in Londonderry playing cowboys and Indians when he triggered a booby-trap bomb hidden in one corner. Doctors at Londonderry's Altnagelvin Hospital tried to save his life by amputating both of his legs but he died.

The victim's father, Billy Gallagher, said the IRA statement represented a major U-turn from the group's 1973 position but it still wasn't good enough.

"I am glad they take full responsibility and accept that they were to blame and no one else was," he said. But he said McGuinness still should be able to provide his family much more detailed information on who did it and why.

Sinn Fein in a statement said McGuinness was in a Republic of Ireland prison in 1973 and so couldn't help the family.

McGuinness -- who since 2007 has been deputy leader of Northern Ireland's power-sharing government -- has repeatedly said he will never provide anyone information on individual IRA members' involvement in bombings and shootings.

In the early 1970s in Londonderry, the predominantly Catholic second-largest city in Northern Ireland, the IRA had several hundred members trying to ambush police and British soldiers, often in the Gallaghers' home district of Creggan.

Billy Gallagher recalled that, in the days after his son's death, two unidentified IRA members came to his door to claim that their unit had planted the bomb but without a detonator. He said the IRA members lied that British soldiers must have added the detonator themselves to make the IRA look bad.

"I never believed that for a second," he told BBC Radio Foyle in Londonderry.

Friday's IRA statement offered its own confusing explanation for its decision to leave a bomb in the Gallaghers' backyard.

The IRA claimed the group decided to call police before the explosion "because of the potential danger to the community." It didn't explain why the group, despite recognizing this civilian danger, didn't simply collect its own bomb.

The statement then claimed that British Army units responded to the IRA call and made it impossible for IRA members to remove the bomb. The statement also said the IRA simultaneously assumed that the British searchers had found and defused the bomb, so the IRA didn't check after the British left. It said Gordon stepped on the bomb the next morning.

Friday's explanation clashes with basic details of the 1973 British Army account. That said an IRA telephone caller had identified a neighboring street to the bomb's actual location and appeared designed to lure troops into the general area for ambush. After the blast that killed Gordon, troops found a second booby-trap bomb nearby that appeared to have been placed in hopes of catching troops responding to the first blast.

The IRA killed nearly 1,800 people during its unsuccessful 1970-1997 campaign to force Northern Ireland out of the United Kingdom. It declared its cease-fire permanent in 2005 and surrendered weapons stockpiles, but small splinter groups continue to mount occasional attacks, particularly in Londonderry.