"We were just going to meet my two older boys in the supermarket when we heard an explosion," said Katherine Walton, 38, from North Carolina who moved to Kenya with her family two years ago.
"I grabbed the girls and started running. A woman pulled us behind a promotional table opposite. I could see the bullets hitting above the shops and hear the screaming all around us."
She remembers only fragments of the hours that followed which she spent huddled under the table but, according to Philip Walton, 39, she saw enough of the attackers to be able to describe several of them in detail afterwards.
"She heard them talking to people, telling them to stand up followed by gunshots," he recalled. "The thing that's troubling her now is she can't forget the smell of the gunpowder."
During their ordeal, the couple's three daughters, aged4, 2 and 13 months, were shielded and calmed by an injured Kenyan woman and two Indian women who hid with them.
"They were so still and quiet," Katherine Walton said. "My baby was screaming when there was shooting but between that, she just slept. In one lull in the fighting, my two-year-old and the baby were playing together with my phone. I couldn't understand how they could be acting like everything was fine."
Metres away from them she saw a man with a pistol who was shooting at a heavily armed young jihadi in a bandana who was taunting him to come closer.
That man was Abdul Haji, who had rushed to the mall after getting a text message from his brother who was trapped inside.
"We saw a lot of dead people. Very young people, children, old ladies, you cannot imagine," Haji told the Kenyan television station NTV.
"From what they were doing, you could tell that these were not normal people. The fact that he was making a joke out of this whole thing made me much more angry and determined to engage them, and to shame them."
Haji said his father taught him to use a gun to protect their cattle from bandits when he was growing up.
Last Saturday, he used his skills to provide fire cover for the Kenyan Red Cross workers and, over a period of three hours, help to evacuate some of the 1000 people who escaped the mall in the initial stages of a siege that would last three days and leave at least 72 people dead. As he stood with a fellow rescuer crouched outside the Nakumatt supermarket, Haji said he noticed the women hiding under the table.
"Just a few minutes ago we were exchanging fire with the terrorists and these people were right in the middle of it, in the crossfire. We regrouped and we started to strategise on how to get them out of there," he said.
He asked the women to move towards them but they indicated they had children with them and could not all run together.
Haji said he asked Katherine Walton if one of the older children could be encouraged to run towards him.
Portia emerged and ran across the deserted corridor.
The moment was captured by Reuters photographer Goran Tomasevic in a dramatic image that was beamed around the world.
Philip Walton, who during the siege was 15,000km away on a business trip to the United States, said he reacted in disbelief when he first saw the photograph of his daughter striking out alone across the mall. "She's not normally the kind of girl that would run to a stranger, particularly one with a gun," he said.
His wife added: "I don't know how she knew to do it but she did. She did what she was told and she went."
Seeing the little girl running towards him gave Haji fresh impetus to continue helping people out.
"This little girl is a very brave girl," he said. "Amid all this chaos around her, she remained calm, she wasn't crying and she actually managed to run towards men who were holding guns. I was really touched by this and I thought if such a girl can be so brave ... it gave us all courage."
One by one, the Walton family emerged and ran with Haji and other rescuers until they reached the police lines outside the mall.
There, Katherine Walton was reunited with her teenage boys who had been trapped with another family in the basement of the mall but also had escaped.
"As we went out, it was so quiet and we started to get upset because we realised we were almost there," Katherine Walton said.
"They soothed us, told us we were okay, we were safe and to stay calm. They did a wonderful job."
Looking at the photograph now, Katherine Walton says she can see the fear etched on her daughter's face. "I was worried about family in America seeing it because we haven't really shared the whole story with them yet," she said. "For me, I know the story behind it and that it ends well. I think I owe Mr Haji a hug or two."
Since he has been identified, many Kenyans have hailed Haji as a hero but he disagrees.
"I think I did what any Kenyan in my situation would have done to save lives, to save other humans regardless of their nationality, religion or creed," he said.
Portia and her big brother have since been sent back to school in an attempt to establish "a new normal", Philip Walton said.
"Our two-year-old cries a little bit more and Portia wants to stand a little closer but really they are doing exceptionally well considering," his wife added.
Philip Walton said there was no question that they would be leaving Kenya. "There will always be bad people in the world but it's the comfort of knowing that there are good people; that matters," he said.
"The way this community drew together and responded was just incredible. It's an honour and a privilege to be able to live among such good people."
"It defies logic that they survived but we're a family of deep faith and take a lot of comfort from knowing that God protected them," he said.
