So its people, I`m supremely confident that Bostonians will pull together

to take care of each other and move forward as one proud city, and as they do,

the American people will be with them every single step of the way.

CARL AZUZ, CNN ANCHOR: City whose heart may be broken, but whose spirit is not.

We want to welcome you to the special edition of CNN STUDENT NEWS.

Today`s entire show is about Monday`s terrorist attack in Boston.

The victims, the reactions, the investigation.

When we produced yesterday`s program, the bombings had just happened.

We didn`t have a lot of details.

We have more now, and that`s where we`ll start things off today.

The two bombs that went off near the finish line of the Boston Marathon exploded 12 seconds apart.

Three people were killed, more than 170 others were wounded.

Early reports about other possible explosives turned out to be wrong.

One runner, Jennifer Tracy was in the marathon and recording on her phone when the first bomb went off.

AZUZ: That was the moment when the day changed.

John Berman fills in the time line leading up to the blast and immediately afterwards.

JOHN BERMAN, CNN CORRESPONDENT: A picture-perfect third Monday in April.

Patriot`s Day and the day of the 117th Boston Marathon.

At 9:32 A.M the elite women racers take off from Hopkinton on the 26.2 mile course on the way to Boston`s Back Bay.

Almost two and a half hours later, the first elite runners start crossing the finish line,

wave after wave of runners, thousands of them follow.

Then about 2:50 in the afternoon, it happens.

BERMAN: An explosion near the finish line.

12 seconds later ...

BERMAN: ... another explosion. About a block up a crowded Boylston Street.

JEFF CURTIS, HELPED VICTIMS: They were banged up bad, severe lacerations, amputees, a lot of shrapnel.

You know, they were pretty big explosions.

They were banged, a lot of blood everywhere.

Emergency teams and law enforcement scramble.

OFFICER: Get all units in this city this scene now please.

OBAMA: This was a heinous and cowardly act,

and given what we now know about what took place, the FBI is investigating it as an act of terrorism.

Anytime bombs are used to target innocent civilians, it is an act of terror.

What we don`t yet know, however, is who carried out this attack or why.

Whether it was planned and executed by a terrorist organization,

foreign or domestic, or was it act of malevolent individual.

But we will find out.

We will find whoever harmed our citizens and we will bring them to justice.

The American people refused to be terrorized,

because what the world saw in the aftermath of the explosions were stories of heroism and kindness and generosity and love.

If you want to know who we are - and what America is, how we respond to evil, that`s it.

Selflessly, compassionately, unafraid.

AZUZ: President Obama met with some of his national security advisers yesterday.

That included the FBI director, the Attorney General and the Secretary of Homeland Security.

They were going over the latest details in the investigation in the attack.

As of Tuesday, authorities didn`t have any suspects,

and they haven`t determined any possible motives for the attack.

The investigation began immediately after the bombing, and the FBI has taken the lead.

RICK DESLAURIERS, FBI SPECIAL AGENT IN CHARGE: Our mission is clear:

to bring to justice those responsible for the marathon bombing.

The American public wants answers, the citizens of the city of Boston and the commonwealth of Massachusetts want and deserve answers.

This group of dedicated men and women standing before you today, pledged to do everything possible to get those answers.

AZUZ: Boston`s police commissioner described the site of Monday`s bombings as the most complex crime scene in the history of our department.

Part of the investigation is focused on what`s called the bomb`s signature.

The idea is that understanding the bombs can help lead authorities to possible suspects,

and even tiny pieces of debris can give clues.

Another way authorities are helping to find answers, is by going through pictures and video.

They`re getting a lot of footage from security cameras that were in the area,

but they are also asking anyone with images from any part of the marathon to share them with police.

JULIETTE KAYYEM, FORMER U.S. ASST. SECY. OF HOMELAND SECURITY: What the police are doing,

is that they`re starting to ask people at the airports to check their iPhones, which is just really smart.

People don`t know that they were witnesses, that they might actually have evidence in their phones or in their cameras,

and so there is no sort of the search amongst all the people that were there,

the tens of thousands of people to say, hey, did you see something?

AZUZ: Tom Foreman now has more on what exactly investigators are looking for.

TOM FOREMAN, CNN CORRESPONDENT: One of the mysteries of this attacks is that they happened so late in the sporting event,

more than 17500 runners had already completed the 26.2 miles, had passed the finish line and gone on their way.

Only about 6,000 remain.

The elite world class runners, who attract so many spectators, had long passed and left and that`s when these explosions happened.

So, what are police looking for?

They`re trying to find any way to see a connection between the people who were along this course before the explosions and the time they happened.

They are asking for video. They are asking for anything that people took in the way photographs along here, to see if there`s some connection.

Did they see some person how appears in the series of pictures or videos who seems to be connected to those explosive points.

If they can find that, that`s a lead, that`s something they can follow,

and then maybe then can solve some of the mysteries of these attacks.

AZUZ: When we put this show together, we had some limited information on the people who died in the Boston attack.

One of them was eight year old Martin Richard.

The boy was watching the marathon with his mother and sister, when the bombs went off.

The blast took Martin`s life, left his mother with the brain injury and his sister, who is six years old, lost a leg.

Yesterday, Martin`s father released a statement saying that his wife and daughter were recovering.

And also said, "We thank our family and friends, those we know and those we have never met, for their thoughts and prayers.

I ask that you continue to pray for my family as we remember Martin."

Flowers were left at the Richard`s home after the bombing, and someone wrote the word, "peace" at the end of their driveway.

Another victim was Krystle Campbell.

And the place she worked for put this note up in its Facebook page yesterday.

"She was an incredible woman, always full of energy an hard at work,

but never too tired to share her love and a smile with everyone.

She was an inspiration to all of us."

The reaction to Monday`s attack in Boston came in from across the country and around the world.

Global leaders spoke out against the violence and offered their thoughts and prayers to the victims and the people of Boston.

President Obama ordered the flag of the White House lowered to half-staff to honor those victims,

the flag at the U.S. Capitol building was at half- staff, too.

Security at those Washington buildings was increased after Monday`s attacks.

Other cities added additional security.

New York, Miami, Chicago, Los Angeles.

And in London, which is set to hold its own marathon in just a few days,

organizers said that race will start with 30 seconds of silence to pay tribute to the attack in Boston.

Moments of silence were held around the U.S. as well, the U.S. House of Representatives paused on Monday after news of the attack.

In New York yesterday, the New York Stock Exchange, normally a scene of noise and energy, held the moment of silence,

and in Atlanta, there was a silent mile.

Runners paying tribute to the people killed and injured in Boston by running a full mile in silence Tuesday morning.

A lot of people turned to social media in the aftermath of Monday`s attacks.

They were sharing their support, some were looking for comfort.

That included some Boston athletes.

Danny Amendola, a wide receiver with the New England Patriots tweeted that he would donate $100 for every pass he catches this season to a Boston Marathon Relief Fund.

$200 for any dropped passes.

And Boston Red Sox player Shane Victorino tweeted that Boston is a tough, resilient town and will prevail over this saddening tragedy.

One quote started circulating around from children`s TV star Mr. Rogers.

He said "When I was a boy, and I would see scary things in the news, my mother would say to me, `Look for the helpers. You will always find people who are helping."

To this day, especially in times of disaster, I remember my mother`s words, and I`m always comforted by realizing that there are still so many helpers, so many caring people in this world."

If you are on Facebook, you`re welcome to share your thoughts and talk about what happened in Boston on our Facebook page.

It`s Facebook.com/cnnstudentnews.

And, of course, all of our thoughts and prayers are with the victims of this tragedy and the people of Boston.

For CNN STUDENT NEWS, I`m Carl Azuz.

END