WASHINGTON (Reuters) – U.S. forces finally found al Qaeda leader Osama bin Laden not in a mountain cave on Afghanistan's border, but with his youngest wife in a million-dollar compound in a summer resort just over an hour's drive from Pakistan's capital, U.S. officials said.

A small U.S. team conducted a night-time helicopter raid on the compound early on Monday. After 40 minutes of fighting, bin Laden and an adult son, one unidentified woman and two men were dead, the officials said.

U.S. forces were led to the fortress-like three-story building after more than four years tracking one of bin Laden's most trusted couriers, whom U.S. officials said was identified by men captured after the September 11, 2001 attacks.

"Detainees also identified this man as one of the few al Qaeda couriers trusted by bin Laden. They indicated he might be living with or protected by bin Laden," a senior administration official said in a briefing for reporters.

Bin Laden was finally found -- more than 9-1/2 years after the 2001 attacks on the United States -- after authorities discovered in August 2010 that the courier lived with his brother and their families in an unusual and extremely high-security building, officials said.