The Provisional wing of the Irish Republican Army claimed responsibility today for the killing last night of the 86-year-old former speaker of the abolished Northern Ireland parliament, Sir Norman Stronge, and his son James, 48, in their country home near the southern border of British-ruled province.

Police assumed the killings were in retaliation for the wounding last week of Catholic activist Bernadette Devlin McAliskey and her husband, Michael. The IRA killed three members of the security forces in the wake of the McAliskey shooting, for which three suspected members of a Protestant terrorist group have been charged with attempted murder.

Devlin and her husband remain in serious condition in a Belfast hospital, with multiple gunshot wounds.

Nothern Ireland police said last night's attack was carefully planned, with at least 10 heavily armed men in combat uniform stealing two cars, and splitting up with two men holding the car owners while eight others attacked the Stronges.

The IRA raiders, after shooting the Stronges and bombing their house last night, were cut off by a four-man police patrol. But the IRA men escaped after a shootout. Police and Army units on both sides of the nearby border between Ulster and the Irish Republic mounted one of the biggest manhunts in Ulster's troubled history.

As security forces brace for retaliatory raids from Protestant terrorists, Ulster politicians were glum about the near future. "We are in a very, very dangerous situation," said a member of Parliament from the province, Gerry Fitt. "I can't see an end to the killing."

Stronge, who was decorated for service in World War I, retired as speaker of the old Protestant-dominated Northern Ireland parliament in 1969 after 45 years as representative of the Protestant Unionist Party.

Britian abolished the parliament when it took over direct rule of Ulster in 1972 to prevent civil war between Ulster's Protestant majority and the Catholic minority.

Last night's murders, condemned by all of Ulster's main political parties and religious leaders as well as by the Catholic-dominated government of the neighboring Irish Republic, are viewed with alarm in Northern Ireland as signaling a trend of terrorists attacking prominent political figures rather than the traditional targets -- security forces or rival terrorist groups.

The recent killings and shootings have shattered hopes for peace in the wake of the recently ended IRA hunger strike by inmates at the Maze Prison. It was called off last month after failing to force the British government to accord convicted IRA terrorists special treatment as "political prisoners."

Police and political sources said today the IRA was both retaliating for the Devlin shooting and attempting to regain waning public support after the hunger strike. They fear increased Protestant attacks in counterretaliation and also to obstruct possible joint political moves by Britian and Ireland aimed at settling the Ulster conflict.

The Protestants have expressed fears of a "sellout," with Britian forcing Northern Ireland into some form of association with Ireland as a result of increasingly close relations between Britian and the Irish Republic.The majority Protestant community historically has fought any merger. The British have said it could only come about with the consent of the people of Northern Ireland.

"It's obvious that the people who attacked Bernadette Devlin and now the Stronges are trying to stir up Northern Ireland and get support by attacking prominent people," said Fitt, who is from a Catholic working-class area of Belfast.

"These latest and most vile murders by the IRA of an old man of 86 and his son, who were unable to defend themselves, will give an indication of the lengths to which these killers will go," he added. Fitt survived an IRA attack four years ago.

Tonight, Protestant politicians in Ulster called for the British government to tighten security on the border with the Irish Republic where the IRA has killed several people, including the Stronges, in the last two years. Despite increased security operations by the Irish government, British officials say the IRA still launches many of its operations from the Irish Republic.