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 US 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 Sept. 11, 2001, attacks on New York and Washington that killed nearly 3,000.

Pakistanis not told

But the operation could complicate relations with Pakistan already frayed over US drone strikes in the west of the country and the jailing of a CIA contractor accused of killing two Pakistani men.

A US official said Pakistani authorities were told the details of the raid after it had taken place.

Obama said US 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 US 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 Sept. 11.

They finally identified the men's residence in August 2010, and quickly realized the $1 million; three-story property was far more than the home of two individuals with no discernible source of wealth.

Possible Reprisals

Authorities said Obama'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 US 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 Center twin towers felled by hijacked airplanes on Sept. 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.

US 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 US 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.