Osama bin Laden, the leader of al Qaeda and the man known as the mastermind behind the horrific attacks against the United States on September 11, 2001 that killed nearly 3,000 people, is dead.

President Obama announced to the American people and the world just after 11:30 p.m. EDT, Sunday, that Osama bin Laden was killed in a mansion in Abbottabad, Pakistan.

The president said after a firefight with U.S. operatives, bin Laden was killed, they took custody of his body and no Americans were harmed during the firefight.

In his speech President Obama said that "Justice has been done."

In New York City, it didn't take long for crowds to gather at Ground Zero in celebration. The few-hundred-strong sang songs, including "We Are the Champions" and "The Star Spangled Banner," as well as voiced chants of "USA, USA" during the hours that followed the president's announcement, according to The Huffington Post.