You are looking at obviously a very disturbing live shot there.

That is the World Trade Center.

And we have unconfirmed reports this morning that a plane has crashed into one of the towers building.

There are no words.

It appears that something hit the Pentagon on the outside of the fifth corridor.

We have a report now that a large plane crashed this morning north of the Somerset County Airport, which is in western Pennsylvania.

It all started at 8 45 on a clear Tuesday morning.

Way had a live camera up on what looked like a smoking slash across one of the World Trade Center towers.

A passenger plane had flown into it, and I remember some of us here at CNN thinking this was some sort of freak event.

Then a second plane flew into the other tower that was at 903 a.

M.

And at that point there was this deepening dread in everyone.

Something was wrong in a way we've never seen before.

Airports, bridges, tunnels in New York and New Jersey shut down within 30 minutes.

President George W.

Bush said we were under an apparent terrorist attack in minutes after that, every airport in the country was closed.

That had never happened before.

It wasn't over, though.

At 9:43 a.m. 1/3 passenger jet crashed into the Pentagon.

Dark smoke rolled up from that part of that huge building.

All lies and many cameras were on that in the two burning towers in New York.

And is all of us watched 10 051 of those towers gave way where it was smoking top part, crushing down on the rest of it and sending up debris boiling great class.

Five minutes later, part of the Pentagon collapsed and 1/4 hijacked jet crashed in a rural part of Pennsylvania White House.

The United Nations, the state and Justice departments, the World Bank all evacuated, America bound Atlantic flights were rerouted to Canada, and the second trade center tower came down at 10 28.

So many closings, evacuations, shutdowns.

Except for emergency response teams, the heroes of 9 11 the country virtually stopped what it was doing and gathered around TV screens.

The president appeared just after 1 p.m. And asked Americans to pray, and there wasn't much else we could do the destruction was MME.

Or less done around 10 30.

It was less than two hours from the first crash, but the change it inflicted was immeasurable.

Maur.

Americans were killed on September 11th 2001 than on the Japanese attack on Pearl Harbor in 1941.

And when President Bush addressed the nation that night at 8 30 his tone was one of sympathy, resolve and warning to anyone who'd planned or supported the attacks.

We will make no distinction between the terrorist who committed these acts and those who harbor them.

In the difficult days that followed, we learned that the Al Qaeda terrorist group led by Osama bin Laden was responsible for all of this.

On America's attention and anger turned to Afghanistan, whose Taliban leaders were giving Al Qaeda a safe place to live and operate on Wednesday at 8:40 a.m. Eastern, near the time when the first hijacked plane hit the north tower of the World Trade Center, the 9 11 Memorial and Museum in New York is holding a ceremony to honor the victims of the September 11th attacks.

This includes the first responders as well more than 400 emergency workers, including firefighters, police officers and medical technicians, gave their lives trying to rescue people in the doomed World Trade Center towers.

The names of the 2700 and 53 people killed in New York City, as well as the hundreds of others killed at the Pentagon in Washington, D.

C.

And in Shanksville, Pennsylvania, will be read at the Pentagon Memorial.

There are 184 benches representing the 184 people who died there.

U.

S President Donald Trump is scheduled to attend an observance ceremony on Wednesday alongside US Defense Secretary Mark T.

Esper and the chairman of the Joint Chiefs of Staff, Marine General Joseph F.

Dunford Junior, and at the Flight 93 National Memorial in Shanksville, Pennsylvania.

The names of the 40 passengers and crew members who were killed there will be read, starting at 10 to 3 a.m. The time when their plane was crashed into the field.

There are events like this planned across America on the 18th anniversary of the 9 11 attacks.

They'll include moments of silence, movie screenings, music, symbolic craft projects, messages of gratitude or hope, all in remembrance of the worst act of terrorism in American history and in honor of the victims and those who gave or risk their lives to save them.

The 9 11 attacks led to the war on terror, an international effort led by the United States to fight terrorism organizations worldwide that began with targeting the Al Qaeda terrorist group in Afghanistan and thousands of American troops remain in the unstable Asian country.

To this day, the beginning of today's show gave you a sense of what it was like to observe the events of September 11th.

As they unfolded, they brought a uniquely challenging experience for the reporters who covered them live.

And this is one of the most memorable shots from that day.

This is Aaron Brown on the roof of CNN's old bureau in midtown Manhattan.

Everyone has a 9 11 story.

Mine starts with hearing the words.

What channel is CNN alone?

We turned on the television and never turned it off.

Aaron Brown helped me, and so many other people feel a little less afraid that day.

He anchored all the way until midnight until one in the morning, and he was never even supposed to be on that air that day at all.

It has just been a huge explosion.

We can see a billowing smoke rising.

And I can tell you that I can't see that second tower.

And we've seen this extraordinarily in frightening scene behind us of this second tower now just encased in smoke.

What is behind it?

I cannot tell you, but just look at that.

That is about it's frightening a scene as you will ever see.

You must have known through that smoke.

There was nothing there, but you couldn't see it yet with your own eyes.

I felt in that moment profoundly stupid.

Uh, why?

I will tell you because I I will tell you that a 1,000,000 things have been running through my mind about what might happen about the the effect of a jet plane hitting people above where the impact was, what might be going on in those buildings.

And it just never occurred to me that they'd come down.

And I thought, It's the only time I thought maybe you just don't have what it takes to do a story like this because it just had never occurred to me.

Let me look at one other moment.

This is the second tower falling when you did seem more prepared for what we were seeing.

There is a large fire at the Pentagon.

The Pentagon has been evacuated.

And there's you can see, perhaps the second tower, the front power, the top portion of which is collapsing.

Good Lord.

There are no words.

Silence is what you used in that moment when you see it.

Now, what stands out to you?

Um, first of all, from the moment the first tower fell, there was a clock ticking.

It was ticking in my head.

It was taking in the heads of hundreds of millions of people, uh, in America and a 1,000,000,000 people around the world who are watching it because if the first tower fell, the 2nd 1 was gonna fall, too.

In that moment, there were men, mostly men, firemen and policemen who were running into that building.

It was collapsing and knowing that they were never going to come out.

And, um, I think when that building fell, I understood better than at any other point in my life before or since What the word hero meant.

It's not that we didn't try to tell that story great.

It set the story itself is too great to tell.

We're at the point now where this really is the history.

It was something that I was fortunate, professionally to do and painful as an American to live through it.

It's a weird contradiction that journalists live with the ambivalence of of on the one hand loving the big story and on the other hand, hating the fact that that story is happening.