The Irish Republican Army (IRA) apologized this week for the 1973 killing of a 9-year-old boy who happened upon a bomb while playing in his backyard.

For decades the group had blamed the British Army for the boy's death, but even after their confession the boy's father said Friday it was not enough.

The IRA admitted killing Gordon Gallagher after calls from the boy’s parents for First Minister Martin McGuinness, believed to have been the IRA leader in Derry at the time, to tell them who planted a bomb in their children’s play area and why.

In a statement the IRA said the group accepted responsibility and was "truly remorseful and profoundly sorry." It offered its apologies "for the pain and grief caused." The statement was made on the eve of the 39 anniversary of Gallagher’s death.

According to a report in the Washington Post, the boy had been running around in their back yard in Derry playing cowboys and Indians when he accidentally triggered a booby-trap bomb hidden in one corner.

Doctors at Derry’s Altnagelvin Hospital tried to save his life by amputating both of his legs but could not save him.

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

Gallagher said 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," Gallagher told BBC Radio Foyle.

In its statement , the IRA claimed it decided to call police before the explosion went off "because of the potential danger to the wider community." British Army units responded to their call, which made it impossible for IRA members to remove the bomb they claimed.

The statement also said the IRA assumed that the British searchers had found and defused the bomb, so the IRA didn’t check it had been made safe after the British left. Gordon Gallagher stepped on the bomb the next morning.

Gordon Gallagher