9/11 attacks: Timeline, facts; What happened on Sept. 11? How many people died?

U.S. Navy photo by Chief Photographer's Mate Eric J. Tilford

An image of the charred remains of the World Trade Center in the wake of the Sept. 11, 2001 attacks.

The deadliest terrorist attack in U.S. history occurred 18 years ago today, shocking the nation and the world.

On the morning of Sept. 11, 2001, 19 hijackers turned airplanes into weapons in a series of four coordinated attacks, killing 3,000 Americans. The majority of those who died were at the World Trade Center in New York, which collapsed hours after they were struck by the planes. Hundreds were also killed when planes crashed into the Pentagon and aboard Flight 93, which was brought down by heroic passengers outside of Somerset County, Pennsylvania. It’s believed Flight 93 was headed to Washington, D.C.

Almost 6,000 people were injured in the attacks, which also caused some $10 billion in property damage. In the years that followed, first responders to the attack died from 9/11-related cancers and respiratory disease.

The attacks led to U.S. wars in Iraq and Afghanistan.

Timeline

Here's a brief recap of the day's events from the History Channel and 9/11 Memorial:

7:59 a.m. - American Airlines Flight 11 takes off from Boston's Logan International Airport en route to Los Angeles with 92 people on board.

8:14 a.m. - United Airlines Flight 175takes off from Boston with 65 people on board; it is also headed to Los Angeles.

8:19 a.m. - Flight attendants aboard Flight 11 alert controllers the plane has been hijacked.

8:20 a.m. - American Airlines Flight 77 takes off from Dulles International Airport outside of Washington, D.C. The Boeing 757 is headed to Los Angeles with 64 people aboard.

8:41 am - United Airlines Flight 93, a Boeing 757 with 44 people aboard, takes off from Newark International Airport en route to San Francisco.

8:46 a.m. - Hijackers crash American Airlines Flight 11 into the North Tower of the World Trade Center between floors 93-99, killing all on board and hundreds inside the building. Hundreds of first responders speed to the scene; many are killed in the collapse of the buildings.

8:50 a.m. - White House Chief of Staff Andrew Card alerts President George W. Bush that a plane has hit the World Trade Center. The president is visiting an elementary school in Sarasota, Florida at the time.

9:03 am - Hijackers crash United Airlines Flight 175 into floors 75-85 of the WTC's South Tower. All on board are killed and hundreds more killed inside the building.

9:08 a.m. - FAA bans all takeoff of flights going to New York City.

9:24 a.m. - The FAA learns Flight 77 has also be hijacked after passengers and crew on board alert family members.

9:37 a.m. -Flight 77 crash the plane into the western facade of the Pentagon in Washington, D.C., killing 59 aboard the plane and 125 military and civilian personnel inside the building.

9:42 a.m. - FAA grounds all flights over continental US. It's the first time such a declaration has been made in the U.S.

9:45 a.m. - The White House and U.S. Capitol building are evacuated.

9:59 am - The South Tower of the World Trade Center collapses.

10:07 a.m. - Passengers and crew aboard hijacked Flight 93 learn about the attacks and attempt to retake the plane. It crashes into a Pennsylvania field, killing all 40 on board.

10:28 a.m. - The World Trade Center's North Tower collapses.

5:20 p.m. - The 47-story Seven World Trade Center collapses after burning for hours.

8:30 p.m. - President Bush addresses the nation, calling the attacks "evil, despicable acts of terror" and declaring that America, its friends and allies would "stand together to win the war against terrorism."

9/11 numbers

• Total number killed in attacks in New York: 2,753
• Number of firefighters and paramedics killed: 343
• Number of NYPD officers: 23
• Number of Port Authority police officers: 37
• Number of employees who died in Tower One: 1,402
• Number of employees who died in Tower Two: 614
• Number of employees lost at the World Trade Center office of Cantor Fitzgerald: 658
• Estimated number of children who lost a parent: 3,051
• Estimated cost of cleanup: $600 million
• Total number killed in attacks in New York: 2,753
• Number of firefighters and paramedics killed: 343
• Number of nations whose citizens were killed in attacks: 115
• Number of families who got no remains of their loved ones: 1,717
• Percentage of Americans who knew someone hurt or killed in the attacks: 20 percent
• Victims ranged in age from two to 85 years. Approximately 75-80 percent of the victims were men.