It began as a celebration but in a terrifying instant became a slaughter. And Fatima and her sisters were caught in the middle of it all.

The suicide blast killed at least 70 people and wounded close to 200 last December. The bomber detonated himself in a street full of worshipers celebrating the Shiite Muslim ceremony Ashura in Kabul.

It was a moment of devastation for Afghanistan - and for one family who had gone to the colorful festival for relief and alms. But thanks to two charities and dozens of dedicated volunteers, the three sisters have not only received medical treatment for their wounds but have been also able to recover from the trauma of the event with a six-week stay in the United States.

Tamima, 11, Fatima, 10, and their sister Gulmina, six, were flown from the desperation of life on the streets of Kabul to the comfortable security of homes in Charlotte, North Carolina.

Before their almost unimaginable journey, the three girls were understandably nervous. They quietly finished packing their small schoolbook bags with a change of clothes and a few mementos. That's all their family could afford to send them on their way. They fretted over each other's hair, trying especially hard to comb out the knots from little Gulmina's shaggy cut.

But finally it was time to say goodbye to everything they knew. Fatima, Gulmina and Tamima hugged their father while their mother, covered head to foot, wished them well with some whispered advice: "Take care of your sisters and remember your ways."

CNN is only identifying the girls by their first names to protect them and their family from possible retaliation by the Taliban.

The horrifying moment of the blast was caught on tape in video obtained by CNN. Among the victims bloodied by the attack were many children, many like Fatima and her sisters who had simply gone to the festival seeking handouts or alms to help their poverty-struck family.

Photographer Massoud Hossaini won a Pulitzer Prize this year for capturing the anguish in the moments after the bomb exploded. From the cover of Time magazine to front pages around the world, all eyes were drawn to the terrified scream of Tarana Akbari, who has come to be known as "the girl in green."

But if you look carefully, you can see Fatima with blood streaming down her face on to her yellow dress and Gulmina is piled among the victims in the background.

UNICEF estimates that there are 50,000 to 60,000 children in Kabul just like the sisters who earn a pittance selling food products and trinkets on city streets. So when thousands of people were crowding the streets to listen to music, eat, socialize and witness the faithful Shia men whip their bodies as a sign of devotion the family saw opportunity both for an exciting day out and a chance to bring in a little money.

The girls have never spoken about the blast outside their family until now. And that came only after weeks of slowly learning to trust the families and their new friends.

"It was after noon...we were in front of the mosque when the bomb exploded and then, the next thing I know, I was bleeding," says Tamima. "Fatima was there, laying on top the bodies of other people."

Gulmina remembers little. "There was a woman behind me, she was screaming. Then I fainted. They took everyone to the hospital and everyone was screaming."

Fatima was in shock from the blast and struggles to explain the minutes after the blast.

"When the bomb exploded, my brother and father were searching for us," she whispers. "There was me and Gulmina and my uncle. But Tamima was lost."

Tamima was wandering, nearly unconscious on her feet, before falling to the ground among the corpses of dozens of other victims.

"A guy came and took me, thinking I was dead," she remembers now. "He zipped me up in a plastic bag and put me down with a lot of other dead bodies."

It was only at that last moment that a U.S. serviceman realized Tamima wasn't dead -- just unconscious and pulled her out of the body bag.

All three sisters were wounded, along with another cousin that lives with them. Tamima was deafened from the blast, the others had nasty gashes and their bodies were peppered with shrapnel.

Hundreds of wounded Afghans flooded into the local hospitals and clinics, quickly overwhelming the ability of doctors and nurses to do anything beyond simply keeping the victims alive.

The girls were hastily stitched up and moved out, leaving huge jagged white scars and bits of bomb fragments scattered through their bodies.

Politically, the mass-scale sectarian attack on Shiite worshipers was unlike anything the country had seen in its decade-long war -- in contrast to Iraq, where violence between Shiites and Sunnis was a major feature of the conflict.

But personally the attack left emotional craters as well. It happened just a short walk from where the charity Skateistan had set up an indoor skateboarding facility where the sisters were among the most frequent visitors - learning English and crafts as well as how to grind a board.

Skateistan's Rhianon Bader said: "I was shocked when the first photo I saw from the blast was of Tamima with blood rushing down her head. We had to do something for them."

The group set about helping the family cope with first the girls' immediate medical needs, and later with surviving the frigid temperatures of Kabul's coldest winter in memory.

With 11 children and many more adults living in the simple mud home -- and only a few windows with glass panes -- it became clear that more needed to be done.

Skateistan was able to raise $4,000 from online donations from around the world to help. They were also able to link up with a specialized charity based in the U.S. state of North Carolina which could really get the medical help the girls needed.

That's where Patsy Wilson picked up. The Charlotte-based executive director of Solace for the Children was in Afghanistan the day of the blast and felt an immediate urge to help.

Solace has been working with Afghanistan since 1997 to bring more than 150 children in need of urgent medical help to the U.S. The charity finds host families and works with hospitals and doctors who volunteer their time and resources to help heal the children.