When Kathy Cunningham's phone rang she "thought it was one of my stupid friends in America that didn't look at what time it was in New Zealand".
"So I let it ring," the American expat said.
"And then it rang again."
This time Cunningham, who now lives in Whanganui, thought she'd better answer it. It was her friend Andrew, who was working in radio at the time.
"He said 'Kath, put on CNN'.
"I did. And I will never, ever, in a million years forget that moment."
The World Trade Centre's north and south towers had been hit by planes hijacked by al-Qaeda terrorists and were billowing smoke.
After about an hour of burning the two towers would collapse, leading to the deaths of 2753 people.
Another hijacked plane was crashed into the Pentagon, killing at least 125 people, and a fourth hijacked plane crashed in a field near Shanksville, Pennsylvania, killing 44 people on board.
Sunday (New Zealand time) marks 20 years since the September 11, 2001 terror attack on the United States of America.
Cunningham spent the 1980s living in Manhattan, around the corner from the Empire State Building. Her sister still lived there at the time of the 9/11 attacks and her brother was in Washington DC.
When she saw what was unfolding on that day she panicked, trying to contact her sister and brother, finally getting through to her mum.
"I was a little alarmed about how close my family were to danger."
All of her family members were safe.
Robi Martin, who has been in Whanganui for four years now, lived in New York at the time of the attacks, but she was in Denver visiting her mother, who woke her with the news.
"She was frantic and telling me all the buildings were falling down and I just had no idea what she was going on about."
Then she saw the pictures for herself.
"Of course you just didn't move the whole rest of the day.
"I remember sitting and just crying and watching the television endlessly that day. Everything came to a total standstill."
After the attacks she remembered not being able to call any of her friends in New York because the phone lines were down for days.
She described the city as being in a "daze" after she returned home from Denver.
"It was just not a normal time."
Another American now living in Whanganui, Amanda Meltzer, had a similar wake-up call to what was happening.
She was just shy of her 21st birthday when she got a call from a friend who told her "to turn on the TV".
"Twenty years later this sentence is burned in my memory of all time. I told him you really shouldn't get upset with what you see on TV," she said.
When she did turn the TV on she couldn't comprehend what she was seeing.
"I remember that being this really defining moment in sort of losing a bit of my childhood and in America we were so used to these movies with special effects, buildings blowing up, gratuitous violence ... and being so immune to it."
When the attacks happened on 9/11 it was the early hours of a Wednesday and that day's edition of the Whanganui Chronicle was about to be sent to print.
"All the staff had gone home, I'd gone home by then too," then editor John Maslin said.
He was getting into bed when the chief subeditor, Roz Lawlor, rang telling him to turn on his TV.
"The memories of it are just the graphics ... the whole thing was just weird.
"The press was all but going to run, Roz and I just discussed it and we came to the conclusion that whatever information we could get, just grab it and rejig the front page and go with it.''
The Whanganui Chronicle was one of the few daily newspapers in the country to get something on its front page about the attacks that morning.
The Whanganui MP at the time, Jill Pettis, now living in Martinborough, remembered the day of the attacks well.
Both her children were living in London and her immediate concern turned to them.
"Is it happening in another big, international and strategically important city in the world?" she asked herself at the time.
Then she rang around people in Whanganui to check how people were coping with the shock.
"Just like me, people back home had children or siblings or close family members overseas too.
"The sense of shock that people were feeling and particularly as we started to see the pictures coming through on TV and people being interviewed at ground zero," she said.
Other than the Pearl Harbour attack more than 50 years earlier, Americans hadn't felt this scale of attack "on their own soil", Pettis said.
It wasn't long before she began thinking about what would follow.
"Some of us thought, no good will come of this.
"What I meant by that was you knew America would retaliate."
Pettis said people are much more aware of the fragilities in the world order today.
"The world has changed and we're not so self-assured about how safe [we are]."
A lot of what Cunningham remembered about her former hometown of Manhattan had changed when she returned to visit for the first Christmas after the terrorist attacks.
She woke up early one day and took the subway towards the World Trade Centre.
"But a lot of the subway stops I was used to no longer existed because of the buildings coming down."
She went to Trinity Church near where the World Trade Centre had stood and tried to understand what had happened to the city she once lived in.
"One of the things that really made me stop was being in that environment ... it was quiet. New York City is not a quiet place at all, anywhere."
Cunningham said her friend worked in the World Trade Centre and had an apartment two blocks away.
He and his wife survived because they were on holiday elsewhere at the time.
"They're alive; they're able to just be so grateful for not being in their offices at that time."
When her friend was able to return to his apartment - many weeks after the attack - it was covered in soot," Cunningham said.
"The power and the force of the collapse of the buildings just pushed all this dirt into his apartment."
After the attacks, Cunningham admitted, she began racially profiling people she was seeing in airports.
"I'm not proud of this.
"I was looking around the airport and thinking, 'oh are you holding a bomb in your briefcase?' ... I was very aware of my environment, much more so than I was anytime when I lived in New York City."
She said she found the increased security measures at airports more of a comfort than a hindrance.
A few years later Meltzer went to New York to interview for medical school and visited ground zero, where the buildings stood.
"it was beyond harrowing. It was just incomprehensible. This doesn't happen to Americans, to people like me."
She went on to study and to treat post-traumatic stress. She had a lot of contact with survivors from 9/11.
But the trauma was spread throughout the world, she said.
"There are not too many days in my life that are emblazoned in my memory like that."