LONDON -- The Irish Republican Army struck at the heart of British government yesterday, launching a mortar attack on the prime minister's Downing Street office and residence as the Persian Gulf war Cabinet was meeting there.
Windows of Downing Street offices, including the Cabinet room, were blown in by one of three mortar shells launched from about 100 yards away from the back of a white Ford van outside the Ministry of Defense in Whitehall, which runs from Trafalgar Square to Westminster and is lined with government departments.
Two men were seen running away from the van, police said. The mortars were said to have been connected to a timing device.
The van burst into flames after the mortar shells were fired through a hole cut in its roof. Last night, police said the van was bought by three men for cash in London last July.
Britain's anti-terrorist chief, Commander George Churchill-Coleman, said the attack was well planned but badly executed. He told reporters: "There is no doubt in my mind that this is the work of the Irish republican terrorist groups, and you should discount from your mind any connection whatsoever with any Arab terrorist organizations."
Prime Minister John Major told the House of Commons later: "I think it is clear from the timing of the attack this morning that . . . it was a deliberate attempt both to kill the Cabinet and do damage to our democratic government. It failed."
In taking responsibility for the attack, the IRA said in Belfast, Northern Ireland, that the assault had been planned since before Mr. Major took over as prime minister from Margaret Thatcher in November.
It was the IRA's second direct attempt in recent years to wipe out the British Cabinet. During the annual Conservative Party conference in October 1984 in Brighton, it bombed the Grand Hotel, where the Cabinet was staying, killing five people and injuring more than 30. Mrs. Thatcher narrowly escaped death.
The mortar attack injured four people -- three officers of the diplomatic security service, who were cut and bruised by debris, and a passer-by who twisted his ankle while fleeing.
The IRA has been using mortar tubes on the backs of vans or trucks against government and police targets in Northern Ireland regularly since the mid-1980s, but yesterday's attack was the first in England.
Terrorism experts said that, despite the lack of victims, the attack gave the IRA a major coup. The outlawed organization showed it was able to strike against its prime target even at a time of intense security because of Iraqi terrorist threats.
But it did not cause any major disruption in the conduct of government. In Parliament, an apparently unshaken Mr. Major faced the routine prime minister's question time, dealing with such diverse issues as heating allowances for the elderly, the plight of possible British prisoners of war in Iraq, the relationship between the pound and the German mark, and budget ' prospects.
On the mortar attack, Mr. Major said: "It is about time they learned democracies cannot be intimidated by terrorism, and we quite rightly regard them with contempt."
Police were trying to establish how the IRA could penetrate one of the most heavily guarded areas of London with a van loaded with mortar tubes and shells. Former Northern Ireland Secretary Mervyn Griffiths asked how a van could be left unattended on the main road leading to Parliament for several minutes when no ordinary motorist would be allowed to stop his car there.
Mr. Major was chairing the daily war Cabinet meeting of key ministers in the ground-floor Cabinet room when the mortar shells landed at 10:08 a.m.
David Mellor, chief secretary of the Treasury, was outlining the cost of the gulf war when the explosion blew out the windows and sent a blast of cold air -- it was the chilliest day here since 1987 -- into the room.
The room's shatterproof glass and blast-resistant curtains protected the Cabinet members from injury, but other nearby windows shattered.
Defense Secretary Tom King, a former Northern Ireland secretary and longtime target of the IRA, advised his colleagues: "Don't look out. Leave."
Mr. Major said: "I think we had better start again somewhere else."
L The Cabinet moved to a safer room and continued its session.
Police said there was extensive damage to the rear of 10 Downing St., the prime minister's 17th-century town house, and to 12 Downing St., the parliamentary chief whip's office.
Home Secretary Kenneth Baker told the House of Commons that the mortars were apparently fired by a timing device or remote control minutes after the van was abandoned.
He said security in the Whitehall and Westminster areas, where thousands of workers and visitors congregate, would be reviewed, but said: "There is a limit to the sort of defensive measures that can be taken."
He noted that the prime minister's house in Downing Street regularly attracted sightseeing groups of children and families and said it was only by chance none were injured.
Jim Bishop, who was working on the Defense Ministry building only feet away from the van when the mortar shells were fired, said: "Part of the top of the van, about 3 feet square, flew back, and three missiles headed across the road."
Other eyewitnesses described hearing one loud explosion and two smaller ones. The major blast was apparently from the mortar shell that landed in the back yard of 10 Downing St., cratering the lawn, scorching the rear of the building and sending a pall of black smoke into the sky.
The other two shells flew over Downing Street and landed in Foreign Office Green, where the canisters lay burning and smoking.
Police cleared the entire Whitehall area, bringing chaos to midmorning London traffic.