(CNN) -- The mastermind of the worst terrorist attack on American soil is dead, U.S. President Barack Obama announced late Sunday night, almost 10 years after the attacks that killed almost 3,000 people.
Osama bin Laden -- the longtime leader of al Qaeda -- was killed by U.S. forces in a mansion outside the Pakistani capital of Islamabad along with other family members, a senior U.S. official told CNN.
In an address to the nation late Sunday night, Obama called bin Laden's death "the most significant achievement to date in our nation's effort to defeat al Qaeda." "Today, at my direction, the United States launched a targeted operation against that compound in Abbottabad, Pakistan," Obama said. "A small team of Americans carried out the operation with extraordinary courage and capability. No Americans were harmed. They took care to avoid civilian casualties. After a firefight, they killed Osama bin Laden and took custody of his body."