U.S. marks anniversary of 9/11- deadliest terrorist attacks in history

Today, Americans are marking 24 years since the September 11, 2001, attacks with solemn ceremonies, volunteer work and other tributes honoring the victims.

Twenty-four years ago, the United States witnessed a series of attacks that changed the course of history. On September 11, 2001, four coordinated attacks orchestrated by suicide hijackers  targeted key locations in the U.S.

Nearly 3,000 people were killed when hijacked jetliners crashed into the World Trade Center, the Pentagon and a field in Pennsylvania.

• Two planes, American Airlines Flight 11 and United Airlines Flight 175, flew into the North and South Towers of the World Trade Center in New York City, 17 minutes apart. The impacts set the towers on fire, trapping people on upper floors and covering the city in smoke. Within two hours, both towers collapsed.
• A third plane, American Airlines Flight 77, struck the Pentagon, the headquarters of the US military near Washington, DC.
• The fourth plane, United Airlines Flight 93, crashed into a field in Shanksville, Pennsylvania, after passengers attempted to overpower the hijackers. It is believed that the hijackers intended to target the U.S. Capitol.

Today, a memorial and museum stand at the site, and the One World Trade Center, or Freedom Tower, rises to 1,776 feet, higher than the original North Tower. The Pentagon was rebuilt within a year, with staff returning to offices by August 2002.

U.S. President Donald Trump and first lady Melania Trump will attend the service at the Pentagon.