The death of al-Qaeda leader Osama bin Laden has brought relief and renewed grief to people who lost family members and friends in the September 11, 2001, attacks on the World Trade Center and the Pentagon. Bin Laden was killed by U.S. forces in Pakistan after a decade-long manhunt that featured several close calls (including a previous report of his death, in 2006) and a onetime bounty of $25 million.

In accordance with Islamic tradition, U.S. forces buried bin Laden at sea within 24 hours of his death. One of his sons was among those also killed.

Responses were mixed around the world, as many people expressed jubilation at finally seeing the end of bin Laden's leadership of the terrorist organization, which featured dozens of videotaped messages released to the world over the years. Crowds outside the White House sang the national anthem. Responses outside Ground Zero were more muted.

Members of al-Qaeda were quick to warn publicly that their holy campaign against the West was not finished. Top U.S. officials warned of possible retaliation attacks and put the country on high alert. Calls for vigilance came from other world leaders as well. Tellingly, leaders in the Arab world said bin Laden's death was long overdue.

Nearly 3,000 people died in the airplane attacks and their aftermath, including more than 300 New York City firefighters. Many others who were nearby or tried to rescue victims on the day remain chronically ill. Surviving family members and friends still gather each September 11 to remember those lost in 2001.

New York and Washington, D.C., were not the only targets of al-Qaeda attacks during bin Laden's tenure as leader — embassy bombings in Africa that killed 224 people, bombings in London and Madrid and Bali, and the attack on the USS Cole feature on any such list — but they were the most emotional and cost the most lives.

CIA forces tracked bin Laden to a compound in Abbottabad, Pakistan, where he was apparently living a life of luxury in a three-story compound. A group of Navy SEALs stormed the compound and killed bin Laden.

U.S. President Obama ordered the operation after receiving credible intelligence of bin Laden's whereabouts. The success of the mission was a stark contrast to years of painstakingly following up clues and leads that evaporated or grew cold. The current operation was the result of four years' worth of cultivating sensitive intelligence. Security officials stressed that if bin Laden had offered to surrender, he would have been captured alive. No such promise came.