OMAGH, Northern Ireland (AP) _ A car bomb tore apart the center of a bustling market town Saturday, killing at least 28 people and injuring more than 200 in the single deadliest blast in decades of conflict in Northern Ireland.

Many of those slain Saturday in Omagh, 70 miles west of Belfast, were unwittingly evacuated closer to the bomb by police acting on a misleading phone warning.

``We have had men, women and children slaughtered here this afternoon, slaughtered by murderers who wanted to murder ... who gave us a totally inaccurate warning,'' said Northern Ireland Police Chief Ronnie Flanagan.

The dead included both Protestants and Catholics, as well as five children: three teen-age girls, a teen-age boy and an 18-month-old girl.

``The carnage, the children, a young baby _ pure black, unrecognizable,'' said Frank Hancock, a shocked resident. ``A young girl down a manhole that we had to pull out. A young lad burning, his hair pure singeing.''

The attack coincided with the 29th anniversary of the deployment of British troops in Belfast, a traditional rallying point for Irish Republican Army supporters. It also came several weeks before President Clinton is to visit Belfast to celebrate Northern Ireland's historic peace accord.

No group claimed responsibility for planting the 500-pound bomb in Omagh, which was crowded with weekend shoppers and families attending a festival. But politicians unanimously blamed IRA dissidents who hope to shatter the IRA's 13-month-old truce and the peace agreement it helped inspire.

IRA dissidents have planted several car bombs in other Northern Ireland towns recently, which have caused many injuries but no deaths because of swift action by police. On July 10, an imminent bombing in London was foiled in a joint British-Irish operation against IRA splinter groups.

Hospital officials said 28 people were killed and 220 were injured. The streets surrounding the bomb site were strewn with glass and rubble and streaked with blood.

``I saw bodies lying everywhere, dead people being zipped into bags,'' said Dorothy Boyle, 59.

``The bodies were lying there with water running over them from burst pipes. There were limbs lying about that had been blown off people,'' she said, noting that one young pregnant woman had lost her legs.

Tyrone County Hospital overflowed with the wounded late Saturday. Some survivors used blown-off doors as makeshift stretchers. Others were ferried by ambulance or helicopter to hospitals in Belfast and Londonderry.

The Rev. John Gilmore, a Catholic priest, gave last rites to dozens of the injured.

``It was just nonstop. There were people on the floors, mattresses and chairs,'' said Gilmore. ``Some of the early ones were very badly injured. Some I anointed on mattresses on the floor.''

A phoned warning to the BBC newsroom in Belfast earlier in the day claimed a bomb had been left outside Omagh's courthouse on High Street, on the west end of town.

Police began directing people away from the area _ many of them east down Market Street. Twenty minutes later the bomb blew up behind the security cordon, tearing apart both buildings and people.

A retired fireman, Paddy McGowan, said his car was ``lifted off the ground'' from the impact of the bomb. He, like many drivers, saw the billowing smoke and ran to the scene to try to help.

``It was absolute carnage, the most horrific I have ever seen,'' McGowan said, shaking. ``There were bodies everywhere, and people covered in blood screaming.''

Clinton, who is scheduled to visit Northern Ireland Sept. 3, condemned the attack. His spokesman said Clinton has no plans to scrap his visit.

``I renew my pledge to stand with the people of Northern Ireland against the perpetrators of violence; they will find no friends here,'' Clinton said in a statement. ``On behalf of the American people, I condemn this butchery.''

Former Sen. George Mitchell of Maine, considered the architect of the peace accord, said the bombers had little public support.

``This is a very tiny minority of cowards and murderers that are trying to destroy a process that is supported by an overwhelming majority of the people of Northern Ireland,'' he said. ``This will obviously have a negative effect, but it will not be a fatal effect, insofar as the peace process is concerned.''

Irish Prime Minister Bertie Ahern vowed that breakaway IRA members _ believed to number no more than 100 and mostly based in the Irish Republic _ would be ``ruthlessly suppressed.''

British Prime Minister Tony Blair, on vacation in France, told the BBC that he found it ``impossible to get in the mind of anyone who could possibly do such a thing.''

At one emergency center in Omagh on Saturday night, people gathered to find out if their friends and relatives had been killed in the blast. Police said the dead were being taken to a temporary mortuary at a nearby British army barracks.

Northern Ireland's moderate Catholic leader, John Hume, said the atrocity was ``carried out by undiluted fascists. Obviously they're trying to impose their will by murder on the people of Ireland, north and south.''

Martin McGuinness, chief negotiator of the IRA-allied Sinn Fein party, said he was ``appalled and disgusted'' by this ``indefensible action.''

``It's designed to wreck the peace process, and everyone should work to ensure that the peace process continues,'' said McGuinness, the IRA's reputed former commander.

The attack harkened back to the province's darkest days, in the 1970s, when the IRA bombed commercial centers in Belfast, Londonderry and England.

Omagh's death toll eclipsed the previous worst single attack in Northern Ireland, when the IRA killed 18 soldiers with two bombs on Aug. 27, 1979.

The IRA killed 21 people in a double bombing of two pubs in Birmingham, England, in Nov. 21, 1974.

The bloodiest day remains May 17, 1974, when three car bombs planted by a pro-British gang fatally wounded 35 people in the Irish Republic.