It was the same in that cramped space, as the hours ticked on and Dunster said she "lost all concept of time."

She learned that one of the people sheltered with her had also been at the Navy Yard in Washington last fall when a gunman killed 12 people. The woman explained the procedures police go through before releasing people during an active-shooter incident, which is why they had to hunker down for so long.

At one point, the little girl got hungry, and one of the employees "dug into her lunch box" and offered a banana. Eventually, the meatballs that were in there were passed down to the child as well. And then one of the staff members found a phone charger too.

"They really went above and beyond," Dunster said, a point she also made in a letter to the store's headquarters. "They must have been so stressed out, and yet they were so comforting and caring."

'Capacity to overcome'

"Preparedness does help," said Maria Mouratidis, a psychologist who specializes in trauma and has treated troops returning from Iraq and Afghanistan.

People should find comfort in the response to the shootings, Mouratidis said. The response on Saturday, which seemed to follow the accepted guidelines — workers and shoppers sheltered in place; police secured the mall before allowing people to leave.

Still, she said, there's an understandable unease from being even tangentially connected to the shootings, coming as they did in such an unlikely setting.

"It shattered the sense of 'I'm safe here,'" said Mouratidis, chairman of the psychology department at Notre Dame of Maryland University. "It's extremely stressful."

Mouratidis said there will be a range of reactions, with those closest to the crime the most seriously affected — particularly if they felt they were in immediate danger or unable to help those who were.

Those farther from danger will likely feel anxious, although that should prove fleeting — and if not, she would advise seeking help.

"We don't want to minimize the traumatic effect," Mouratidis said. "But not every stressful event is traumatic."

Even those who have seen the worst, though, can take heart, she said. One of the most gratifying parts of her field, she has learned, is that when you study trauma, what you're also studying is resilience — and she has seen it even in the most traumatic of events.

"We have to trust in our capacity to overcome and to bounce back," she said, "and in how we are actually quite durable."