September 11, 2001: Background and timeline of the attacks

(CNN)Here is a look at the terrorist attacks of September 11, 2001.

Nineteen men
hijacked four fuel-loaded US commercial airplanes bound for west coast destinations. A total of 2,977 people were killed in New York City, Washington, DC and outside of Shanksville, Pennsylvania.
The attack was orchestrated by al Qaeda leader Osama bin Laden.
The Victims:
At the World Trade Center (WTC) site in Lower Manhattan, 2,753 people were killed when hijacked American Airlines Flight 11 and United Airlines Flight 175 were intentionally crashed into the north and south towers or as a result of the crashes.
    Of those who perished during the initial attacks and the subsequent collapses of the towers, 343 were New York City firefighters, 23 were New York City police officers and 37 were officers at the Port Authority.
    The victims ranged in age from two to 85 years. Approximately 75-80% of the victims were men.
    At the Pentagon in Washington, 184 people were killed when hijacked American Airlines Flight 77 crashed into the building.
    Near Shanksville, Pennsylvania, 40 passengers and crew members aboard United Airlines Flight 93 died when the plane crashed into a field. It is believed that the hijackers crashed the plane in that location, rather than their unknown target, after the passengers and crew attempted to retake control of the flight deck.
    As of August 2016, 1,640 (or 60%) of 2,753 WTC victims' remains have been positively identified, according to the medical examiner's office.
    September 11, 2001
    - 8:46 a.m. ET - American Airlines Flight 11 (traveling from Boston to Los Angeles) strikes the north tower of the World Trade Center in New York City.
    - 9:03 a.m. ET - United Airlines Flight 175 (traveling from Boston to Los Angeles) strikes the south tower of the World Trade Center in New York City.
    - 9:37 a.m. ET - American Airlines Flight 77 (traveling from Dulles, Virginia, to Los Angeles) strikes the Pentagon Building in Washington.
    - 9:59 a.m. ET - South tower of WTC collapses in approximately 10 seconds.
    - 10:03 a.m. ET - United Airlines Flight 93 (traveling from Newark, New Jersey, to San Francisco) crashes in a field near Shanksville, Pennsylvania.
    - 10:28 a.m. ET - North tower of WTC collapses. The time between the first attack and the collapse of both World Trade Center towers is 102 minutes.
    December 13, 2001 - The US government releases a tape in which Osama bin Laden takes responsibility for the attacks.
    December 18, 2001 - Congress approves a measure to allow the president to designate September 11th as "Patriot Day" on each anniversary of the attacks.
    December 2001-June 15, 2004 - The original Victims Compensation Fund processes death and injury claims from families and relatives of September 11 victims. Families of those killed had until December 22, 2003, to apply for compensation. The fund reopens in 2011.
    May 24, 2007 - The Chief Medical Examiner of New York City, Dr. Charles S. Hirsch, rules that the death of Felicia Dunn-Jones in 2002, from dust exposure, is directly linked to the 9/11 attack and therefore a homicide.
    July 19, 2007 - The New York Medical Examiner's Office announces that the remains of three more people are positively identified. 1,133 victims, 41% of the total, remain unidentified.
    January 2009 - The medical examiner's office rules that Leon Heyward, who died the previous year of lymphoma and lung disease, is a homicide victim because he was caught in the toxic dust cloud just after the towers collapsed.
    June 17, 2011 - The New York medical examiner rules that Jerry Borg's death on December 15, 2010, is a result of inhaling toxic substances from the dust cloud generated by the collapsing twin towers.
    January 2, 2011 - President Barack Obama signs James Zadroga 9/11 Health and Compensation Act of 2010, reopening and expanding the scope of the VCF.
    September 11th Victim Compensation Fund:
    The original fund operated from December 2001 to June 2004.
    The initial Victim Compensation Fund received 7,408 applications for both death claims and personal injury claims.
    The fund made awards in 5,560 of those cases.
    The reopened and expanded fund has operated since January 2, 2011. Information on total awards is updated regularly and posted here.
    Families who agreed to get compensation from the federal fund agreed not to sue the airlines.
    Economic Impact:
    $500,000 -
    Estimated amount of money it cost to plan and execute the 9/11 attacks.
    $123 billion - Estimated economic loss during the first 2-4 weeks after the World Trade Center towers collapsed in New York City, as well as decline in airline travel over next few years
    $60 billion - Estimated cost of the WTC site damage, including damage to surrounding buildings, infrastructure and subway facilities.
    $40 billion - Value of the emergency anti-terrorism package approved by the US Congress on September 14, 2001.
    $15 billion - Aid package passed by Congress to bail out the airlines.
    $9.3 billion - Insurance claims arising from the 9/11 attacks.
    Cleanup at Ground Zero:
    May 30, 2002 -
    Cleanup at Ground Zero officially ends.
    It took 3.1 million hours of labor to clean up 1.8 million tons of debris.
    The total cost of cleanup was $750 million.
    Homeland Security:
    The Department of Homeland Security was created in response to September 11.
    It merged 22 governmental agencies into one, including the Customs Service, the Immigration and Naturalization Service, the US Coast Guard and the Federal Emergency Management Agency.
    The Department of Homeland Security placed 130 US inspectors at ports in major European, Asian and Muslim nations, as well as strategically-located ports, to inspect cargo for nuclear, chemical or biological weapons being smuggled into the US.
    March 12, 2002 - The Homeland Security Advisory System is introduced.
    April 26, 2011 - The National Terrorism Advisory System (NTAS) replaces the color-coded Homeland Security Advisory System (HSAS).