WASHINGTON (Reuters) - Al Qaeda leader Osama bin Laden was killed in a firefight with U.S. forces in Pakistan on Sunday, ending a nearly 10-year worldwide hunt for the mastermind of the September 11 attacks.
"Justice has been done," President Barack Obama declared in a hastily called, late-night White House speech announcing the death of the elusive head of the militant Islamic group behind a series of deadly bombings across the world.
Bin Laden's death is highly symbolic but it was unclear whether it would mark a turning point in the worldwide war against a highly fractured network of militants, or end any sooner the battle against the Taliban in Afghanistan
A source familiar with the U.S. operation said bin Laden was shot in the head. His death was confirmed separately by officials in Pakistan.
Jubilant, flag-waving celebrations erupted in Washington and New York. It was the biggest national security victory for Obama since he took office in early 2009 and could give him a political boost as he seeks re-election in 2012.
Obama may now find it easier to wind down the nearly decade-old war in Afghanistan, begun after the September 11, 2001, attacks on New York and Washington that killed nearly 3,000.
But the operation could complicate relations with Pakistan already frayed over U.S. drone strikes in the west of the country and the jailing of a CIA contractor accused of killing two Pakistani men.
A U.S. official said Pakistani authorities were told the details of the raid after it had taken place.
Obama said U.S. forces led a targeted operation that killed bin Laden in a compound in Abbotabad north of Islamabad. No Americans were killed in the operation and they took care to avoid civilian casualties, he said.
Bin Laden and three adult men, including a son of bin Laden were killed along with a woman who was used as a shield by a male combatant, officials said.
The operation took under 40 minutes. A U.S. helicopter was lost due to a mechanical problem and its crew and assault force safely evacuated.
The operation was monitored in real-time by CIA Director Leon Panetta and other intelligence officials in a conference room at CIA headquarters in Langley, Virginia, an official said.
Senior administration officials said they were finally led to bin Laden after more than four years tracking one of his trusted couriers, and the man's brother, using intelligence obtained from detainees captured after September 11.
They finally identified the men's residence in August 2010, and quickly realized the $1 million (599 thousand pounds), three-story property was far more than the home of two individuals with no discernible source of wealth.
Authorities said Osama's hideaway, built in 2005, was about eight times larger than other homes in the area, located when it was built at the end of a narrow dirt road. It had security features including 12- to 18-foot walls topped with barbed wire, internal walls for extra privacy, and access controlled through two security gates.
It had no telephone or Internet connection.
Bin Laden's death triggered a travel alert for Americans worldwide, the U.S. State Department said, warning of the potential for anti-American violence.
Thousands of people gathered outside the White House, waving American flags, cheering and chanting "USA, USA, USA." Car drivers blew their horns in celebration and people streamed to Lafayette Park across from the street, as police vehicles with their lights flashing stood vigil.
"I'm down here to witness the history. My boyfriend is commissioning as a Marine next week. So I'm really proud of the troops," Laura Vogler, a junior at American University in Washington, said outside the White House.
Similar celebrations erupted in New York's Ground Zero, site of the World Trade Centre twin towers felled by hijacked airplanes on September 11.
A market perception that the death of bin Laden reduced the security risks facing the United States lifted the dollar from a three-year low and raised stock index futures.
U.S. crude oil prices also fell. "Current oil prices are regarded by most analysts as carrying significant risk premium at current levels and good news on the geopolitical front has the potential to move prices back below $100," said Ric Spooner, chief analyst at CMC Markets in Sydney
However, some analysts said the market impact would be short lived.
Many Americans had given up hope of finding bin Laden after he vanished in the mountains of Afghanistan in late 2001.
Intelligence that originated last August provided the clues that eventually led to bin Laden's trail, the president said. A U.S. official said Obama gave the final order to pursue the operation last Friday morning.
"The United States has conducted an operation that killed Osama bin Laden, the leader of al Qaeda and a terrorist who is responsible for the murder of thousands of men, women and children," Obama said.
Former President George W. Bush, who vowed to bring bin Laden to justice "dead or alive" but never did, called the operation a "momentous achievement" after Obama called him with the news.
Martin Indyk, a former U.S. assistant secretary of state for near eastern affairs, described bin Laden's death as "a body blow" to al Qaeda at a time when its ideology was already being undercut by the popular revolutions in the Arab world.
Other experts were more cautious. "It changes little in terms of on-the-ground realities -- by the time of his death bin Laden was not delivering operational or tactical orders to the numerous al Qaeda affiliates across the world," said Rick Nelson of the Centre for Strategic and International Studies in Washington.
Statements of appreciation poured in from both sides of Washington's political divide. Republican Senator John McCain declared, "I am overjoyed that we finally got the world's top terrorist."
Israeli Prime Minister Benjamin Netanyahu called the death of bin Laden a "resounding triumph" for Washington and its allies.
India said the killing underlined its concern that "terrorists belonging to different organizations find sanctuary in Pakistan," India's home ministry said in New Delhi.
Having the body may help convince any doubters that bin Laden is really dead.
The United States is conducting DNA testing on bin Laden and used facial recognition techniques to help identify him, a U.S. official said on Monday.
The United States is ensuring that bin Laden's body is being handled in accordance with Islamic practice and tradition, a U.S. official said.
Bin Laden had been the subject of a search since he eluded U.S. soldiers and Afghan militia forces in a large-scale assault on the Tora Bora mountains of Afghanistan in 2001.
The trail quickly went cold after he disappeared and many intelligence officials believed he had been hiding in Pakistan.
While in hiding, bin Laden had taunted the West and advocated his militant Islamist views in videotapes spirited from his hideaway.
Besides September 11, Washington has also linked bin Laden to a string of attacks -- including the 1998 bombings of American embassies in Kenya and Tanzania and the 2000 bombing of the warship USS Cole in Yemen.
Additional reporting by Patricia Zengerle, Arshad Mohammed, Alister Bull, Missy Ryan, Mark Hosenball, Richard Cowan, Kristin Roberts, Andrew Quinn and Tabassum Zakaria, Joanne Allen; Writing by Steve Holland; editing by David Storey