Two bombs exploded Monday and two more were found in a "necklace of death" around the house of a senior civil servant responsible for improving relations between Ulster's Protestants and Catholics, police said.

Sir Kenneth Bloomfield, 57, chief of the Northern Ireland Civil Service, and his wife and son were treated for shock from the blasts and released from a hospital.Their home at Helen's Bay, 10 miles northeast of Belfast, was severely damaged in the two explosions at 6:15 a.m. and other nearby houses also were damaged, police said.

The Irish Republican Army did not immediately claim responsibility for the attack, but its guerrillas were suspected because each bomb contained 20 pounds of Semtex, a Czech-made plastic explosive smuggled to the IRA by Libya, police said.

IRA gunmen shot to death a prominent Protestant Friday on a crowded commuter train and the Royal Ulster Constabulary predicted a "horrific" escalation of of violence by the IRA through the end of the year.

In the province so far in 1988, the IRA has killed 34 members of security forces and 77 in all have died in sectarian violence.