Ten years ago, my New Orleans hotel shook like a speeding freight train.

Hurricane Katrina's deadly winds tore up roofs, yanked trees from the ground, and pushed towering walls of seawater miles past the coast.

I am still haunted by what I saw as the Big Easy collapsed into chaos.

A dead man lay slumped in a chair outside the New Orleans convention center, his elderly body covered in a yellow blanket.

A sea of hungry and thirsty people sat nearby, their faces sunken in defeat and despair as they waited day after day for help to arrive.

An exhausted mother limped barefoot across a metal bridge as she clutched her five-day-old baby and told me of a frantic escape across a plank and through a neighbor's window as the floodwaters swallowed her home.

A squad of heavily-armed soldiers -- who had been given shoot-to-kill orders -- marched into the glow of our headlights as we drove through the pitch-black French Quarter.

More than 1,800 people were killed after Katrina ravaged the US Gulf Coast on August 29, 2005. Most of the dead were in New Orleans.

Some 80 percent of the low-lying city was engulfed by filthy water that rose as high as 20 feet (six meters) after poorly-maintained levees burst.

Tens of thousands of people were trapped when the city became a sweltering swamp. Supply trucks didn't arrive with food and fresh water until the fifth day.

Those five days felt like five years.

- Rooftops barely visible -

Freelance photographer James Nielsen and I slipped out of our hotel not long after the eye of the storm passed on the morning of August 29, a Monday -- bracing ourselves against buildings as we looked for signs of damage amid the pounding rain and powerful wind.

The older parts of New Orleans -- the French Quarter, Garden District and central business district -- escaped the worst of Katrina's wrath because they were built on higher ground.

So it took a few hours for us to understand how bad things were.

My heart sank when we pulled up behind an ambulance parked on a freeway overpass and I realized the triangles poking out of the water were rooftops.

We watched a boat pull up to a nearly submerged house where an elderly man needed help getting out through his window.

We woke Tuesday to find that the water had risen even higher after a canal was breached.

Nielsen and I followed a military convoy to a bridge leading into the flooded Lower Ninth Ward, where I met the young mother and a woman who saw her husband get swept away by the storm surge as they tried to reach shelter.

We saw some looting in the French Quarter, but the mood remained relatively festive that day.

I found a restaurant that was serving warm beer and hot gumbo: the power was out, but the gas stove was still working and they wanted to cook up all their food before it spoiled. I spoke to residents with barbecues who were doing the same that night.

- Despair, desperation, fear -

The mood darkened on Wednesday.

People grateful to be rescued from their flooded homes had found themselves dumped at the downtown convention center with no food, water, medical attention or functioning toilets. A fire broke out in a looted shoe store on flooded Canal Street. Hotels were kicking out their guests.

Frightened, thirsty people fled rumors -- mostly false -- of mayhem and violence and camped out on the freeways under a punishingly hot sun.

A shell-shocked intensive care nurse told me how medical evacuation helicopters carrying babies were grounded by the sound of gunfire.

Thursday was a nightmare. I spent the morning talking to refugees on the freeway who kept asking me how the US government could send help across the world but could not manage to take care of its own citizens.

Then I waded through the foul floodwaters to check on the evacuation of the Superdome, a sports arena used as an emergency shelter where 26,000 people had been trapped with scant supplies. The stench of urine and feces was unbearable.

People were so desperate for help that babies were being passed forward over the throngs pressing up against the barricades to get out. I wept at that memory this week and still cannot believe I saw it happen in America.

On Friday, a tough-looking sheriff's deputy broke down into tears as he told me of inmates who drowned in their cells or got caught in razor wire after trying to jump out of the flooded prison.

He could not understand why the deputies and their families were left behind to spend Thursday night on a freeway after the prisoners were evacuated.

While we were talking, a helicopter landed nearby. Help had finally reached him.

- Life-changing experience -

I stayed another week as the military managed to restore order and evacuate all but the most stubborn residents.

I have returned to New Orleans many times to report on its recovery from Katrina and then on the impact of the BP oil spill. I even managed to learn to love the Big Easy.

But those first five days changed me.

I was a cub reporter when my editors sent me to cover Katrina.

I lost my faith in government and am still angry about the people who suffered or died because of the botched response.

I found my faith in humanity deepened by the countless acts of selfless bravery and kindness that I witnessed -- like the man who spent days ferrying his neighbors out of the flood zone and wouldn't waste a minute to talk to a reporter.

I never learned his name.