What happened on 9/11, 19 years ago

• The terror attacks on September 11, 2001, were the deadliest attacks on US soil since the Pearl Harbor bombing that launched the US into World War II. The plane hijackings that struck the World Trade Center, the Pentagon, and a Pennsylvania field killed 2,977 people.
• The attacks started at 8:46 a.m., with American Flight 11 hitting the World Trade Center's North Tower.
• The attacks dramatically changed the US, and started the "War on Terror," which targeted the Al-Qaeda extremist group and its leader, Osama bin Laden.

It's the 18th anniversary of September 11, 2001, the date of the deadliest attacks on US soil since the Japanese bombed Pearl Harbor in World War II.

Nearly 3,000 people died in the 9/11 attacks, which The New York Times called the "worst and most audacious terror attack in American history."

The nation is still working to move past the tragedy, and to effectively combat the techniques and ideology of terrorism that seeks to kill and maim as many people as possible.

These photos tell the story of what happened that morning, much of which was captured on live television to a shocked nation.

The morning of September 11, 2001, started off like any other. The Twin Towers stood tall in the Financial District, as they had for more than 30 years.

Fernando Llano / AP

At 8:46 a.m., American Flight 11 crashed into the North Tower of the World Trade Center. At first, newscasters weren't sure whether it was an accident or a deliberate attack.

REUTERS/REUTERS TV

At 9:03 a.m., United Flight 175 crashed into the South Tower, leaving no doubt that this was an attack. Some news channels captured the moment on live television.

A jet airliner is lined up on one of the World Trade Center towers in New York Tuesday, Sept. 11, 2001.      AP

The second plane exploded upon impact, caused by the ignition of its fuel. Now both buildings were burning.

Smoke, flames and debris erupts from one of the World Trade Center towers as a plane strikes it Tuesday, September 11, 2001. The first tower was already burning following a terror attack minutes earlier.      AP Photo/Chao Soi Cheong

People stared from the windows of the Towers, trapped by smoke and flames and destroyed staircases.

People look out of the burning North tower of the World Trade Center in New York City September 11, 2001. Both towers were hit by planes crashing into the buildings. Shortly after this photo was taken this tower fell.      REUTERS/Jeff Christensen

This iconic photo captured a man falling from the North Tower. At least 200 people fell or jumped from the Towers.

A person falls from the north tower of New York's World Trade Center Tuesday Sept. 11, 2001.      AP

At 9:40 a.m., American Flight 77 crashed into the Pentagon. Five minutes later, for the first time in history, the FAA ordered all aircraft to land at the nearest airport.

The U.S. Pentagon is on fire after a hijacked aircraft crashed into it, September 11, 2001.      REUTERS/Hyungwon Kang

At 9:59 a.m. the South Tower collapsed.

The World Trade Center tower two turns into a mushroom cloud as it falls to the ground, September 11, 2001.      REUTERS/Jeff Christensen

People fleeing the scene by foot were covered in dust and ash.

People make their way amid debris near the World Trade Center in New York Tuesday Sept. 11, 2001.      AP

At 10:03 a.m., hijacked flight United Flight 93 crashed into a field in Shanksville, Pennsylvania. The plane's target was believed to be the US Capitol. The passengers on board tried to gain control of the flight and divert the hijackers after learning of the other attacks.

An FBI aerial photograph, taken Wednesday, Sept. 12, 2001, shows the crash site of hijacked United Airlines Flight 93 in Shanksville, Pa. The Boeing 757 was headed from Newark, N.J., to San Francisco when it made an abrupt turn near Cleveland and veered back east across Pennsylvania before crashing in Shanksville, killing all 44 aboard. Flight 93 was the fourth plane to crash in a coordinated terrorist attack.      AP Photo/FBI

At 10:28 a.m. the North Tower collapsed. It took only 12 seconds for the Towers to fall.

Shortly after this photo was taken, the tower fell.      REUTERS/Jeff Christensen

2,753 people were killed in the New York attack.

An aerial view of the World Trade Center disaster site seen on September 18, 2001.      REUTERS/NYC Office of Emergency Management

That number includes 343 firefighters and paramedics and 60 police officers who rushed to help in the aftermath.

REUTERS/Anthony Correia

Another 40 people were killed in Pennsylvania and 184 died in Washington, DC, for a total of nearly 3,000 people.

REUTERS/Larry Downing

Rescue efforts at Ground Zero continued until October 9, and the flames from the collapse burned until December 20.

REUTERS/Shannon Stapleton

In the months after 9/11, the nation came together to help those affected by the attacks. Blood banks were overwhelmed with donations, and hundreds of people volunteered to sift through rubble at Ground Zero.

REUTERS/Ryan Remiorz

After the terrorist attacks, President Bush declared a "War on Terror," targeting the Al Qaeda terrorists responsible for the attack. Al Qaeda's leader, Osama Bin Laden, was killed 10 years later. The national response included a large expansion of America's security efforts.

REUTERS/Larry Downing

In the years after the attack, a Tribute in Light marked the spot where the towers once were.

The Tribute in Light rises above the lower Manhattan skyline and One World Trade Center, left, in a test of the memorial light display, Monday, Sept. 9, 2013 in New York.      AP

Now, the 9/11 Memorial is open to the public to commemorate the tragedy.

AP