They Don't Remember Their Parents Dying On 9/11. But They'll Never Forget

Twenty years ago this week, on Sept. 11, 2001, terrorists launched coordinated attacks on the U.S. using airplanes as their weapons.

Nearly 3,000 people were killed.

Many of those who died left behind children who were so young they never got to know their parents. A new generation has grown up over the past two decades with few if any memories of those they lost; perhaps just a hazy glimpse that continues to fade over the years, or a faint echo of a voice.

These are some of their stories.

"How do I define myself without the most important male role model in my life?"

An Nguyen smiles as he flips through some old family photos: there he is, a 1-year-old, cuddling on his father's lap. A 3-year-old, riding high on his dad's shoulders at their home in Fairfax, Va.

But then there he is, having just turned 4, wearing a traditional Vietnamese white headband for mourning, weeping over his father's casket.

"Being so young and so vulnerable," An says, "it was a really difficult time."

An's father, Khang Nguyen, was an electronics engineer who worked as a contractor for the Navy. He was killed when American Airlines Flight 77 crashed into the Pentagon — a direct hit in the area where he worked. He was 41.

There's a family photo of An — a small boy in khaki overalls, standing outside the Pentagon — taken just a few days after the attack. He's clutching an orange safety fence. Where the plane struck the building, a whole section is gone. There's just a blackened, gaping hole, open to the sky.

Khang Nguyen was born in Vietnam. He grew up amidst the trauma of war, and emigrated from Vietnam