Osama Bin Laden

Osama bin Laden, the mastermind of the most devastating attack on American soil in modern times and the most hunted man in the world, was killed in a firefight with United States forces in Pakistan, President Obama announced on Sunday.

In a late-night appearance in the East Room of the White House, Mr. Obama declared that “justice has been done” as he disclosed that American military and C.I.A. operatives had finally cornered Bin Laden, the leader of Al Qaeda, who had eluded them for nearly a decade. American officials said Bin Laden resisted and was shot in the head. He was later buried at sea.

The news touched off an extraordinary outpouring of emotion as crowds gathered outside the White House, in Times Square and at the ground zero site, waving American flags, cheering, shouting, laughing and chanting, “U.S.A., U.S.A.!” In New York City, crowds sang “The Star-Spangled Banner.” Throughout downtown Washington, drivers honked horns deep into the night.

“For over two decades, Bin Laden has been Al Qaeda’s leader and symbol,” the president said in a statement broadcast around the world. “The death of Bin Laden marks the most significant achievement to date in our nation’s effort to defeat Al Qaeda. But his death does not mark the end of our effort. There’s no doubt that Al Qaeda will continue to pursue attacks against us. We must and we will remain vigilant at home and abroad.”

Bin Laden’s demise is a defining moment in the American-led fight against terrorism, a symbolic stroke affirming the relentlessness of the pursuit of those who attacked New York and Washington on Sept. 11, 2001. What remains to be seen, however, is whether it galvanizes Bin Laden’s followers by turning him into a martyr or serves as a turning of the page in the war in Afghanistan and gives further impetus to Mr. Obama to bring American troops home.

How much his death will affect Al Qaeda itself remains unclear. For years, as they failed to find him, American leaders have said that he was more symbolically important than operationally significant because he was on the run and hindered in any meaningful leadership role. Yet he remained the most potent face of terrorism around the world, and some of those who played down his role in recent years nonetheless celebrated his death.

Given Bin Laden’s status among radicals, the American government braced for possible retaliation. A senior Pentagon official said late Sunday that military bases in the United States and around the world were ordered to a higher state of readiness. The State Department issued a worldwide travel warning, urging Americans in volatile areas “to limit their travel outside of their homes and hotels and avoid mass gatherings and demonstrations.”

The strike could deepen tensions with Pakistan, which has periodically bristled at American counterterrorism efforts even as Bin Laden evidently found safe refuge on its territory for nearly a decade. Since taking office, Mr. Obama has ordered significantly more drone strikes on suspected terrorist targets in Pakistan, stirring public anger there and prompting the Pakistani government to protest.

When the end came for Bin Laden, he was found not in the remote tribal areas along the Pakistani-Afghan border where he has long been presumed to be sheltered, but in a massive compound about an hour’s drive north from the Pakistani capital of Islamabad. He was hiding in the medium-sized city of Abbottabad, home to a large Pakistani military base and a military academy of the Pakistani Army.

The compound, only about a third of a mile from the academy, is at the end of a narrow dirt road and is roughly eight times larger than other homes in the area, but had no telephone or Internet connections. When American operatives converged on the house on Sunday, Bin Laden “resisted the assault force” and was killed in the middle of an intense gun battle, a senior administration official said, but details were still sketchy early Monday morning.

The official said that military and intelligence officials first learned last summer that a “high-value target” was being protected in the compound and began working on a plan for going in to get him. Beginning in March, Mr. Obama presided over five national security meetings at the White House to go over plans for the operation and on Friday morning, just before leaving Washington to tour tornado damage in Alabama, gave the final order for members of the Navy Seals and C.I.A. operatives to strike.

Mr. Obama called it a “targeted operation,” although officials said one helicopter was lost because of a mechanical failure and had to be destroyed to keep it from falling into hostile hands.

In addition to Bin Laden, three men were killed during the 40-minute raid, one believed to be his son and the other two his couriers, according to an American official who briefed reporters under White House ground rules forbidding further identification. A woman was killed when she was used as a shield by a male combatant, the official said, and two others wounded.

“No Americans were harmed,” Mr. Obama said. “They took care to avoid civilian casualties. After a firefight, they killed Osama bin Laden and took custody of his body.” Muslim tradition requires burial within 24 hours, but by doing it at sea, American authorities presumably were trying to avoid creating a shrine for his followers.

The whereabouts of Ayman al-Zawahri, Al Qaeda’s second-in-command, were unclear.

Bin Laden’s death came nearly 10 years after Qaeda terrorists hijacked four American passenger jets, crashing three of them into the World Trade Center in New York and the Pentagon outside Washington. The fourth hijacked jet, United Flight 93, crashed into the Pennsylvania countryside after passengers fought the militants.

“This is important news for us, and for the world,” said Gordon Felt, president of the group, Families of Flight 93. “It cannot ease our pain, or bring back our loved ones. It does bring a measure of comfort that the mastermind of the September 11th tragedy and the face of global terror can no longer spread his evil.”

The mostly young people who celebrated in the streets of New York and Washington saw it as a historic moment, one that for many of them culminated a worldwide manhunt that started when they were children.