The floor beneath her desk collapsed and suddenly Summer Shalders was thrown into darkness.
When the earthquake stopped, the young woman, then only 23, tried to move but a six tonne concrete beam had landed on her pelvis.
That horrifying experience in the rubble of the PGC Building would go on to permanently change her life but, in the years since, Shalders has made an incredible recovery that defied medical diagnosis.
Her determination began soon after the February 2011 quake in Christchurch, when a doctor told her she would never walk again.
“They'd told my mum that I was on amputation watch,” she said, recalling the experience ahead of the 10th anniversary of the earthquake.
“And at the time my mum said, ‘don't you listen to him’. I said, ‘don't worry, I've not even been given the chance to walk again, I'm not listening to him.'”
These days she has well and truly proved that doctor wrong, relearning how to walk through several years of hard work and determination.
Speaking to 1 NEWS from her home in Christchurch earlier this month, the only hint was some tape on the toes of her right foot, which remains numb from a dead nerve in her leg.
The feat is incredible when you consider the horror of that day.
“I got under my desk, and it just happened so quickly,” she said, recalling the mayhem of the disaster.
“I couldn't even see my hand in front of my face, it was so black, and there was the smell of smoke, and I thought, ‘oh my gosh, I'm going to burn to death’.”
It was in the total darkness, she realised that six tonne concrete beam had landed on her pelvis.
“[What] I had to do was just grab my hands like this,” she said, clasping her hands together, “and move my head from side to side, because I lost feeling waist down pretty quickly.
“I started losing the feeling up my body as well, hence why I started to just keep the blood flowing.
“Annoyingly my phone was near me buzzing away, but I couldn't reach it, so that was frustrating, because you just want to talk to somebody that you know.”
Soon the voices of rescuers and others who were trapped could be heard, and a fireman and civilian builder cut their way through the rubble and down to her.
In the mayhem, it took five hours to find a way to get her out.
“It was getting pretty tough by the end there, the fireman was using the jaws of life and airbags to try and lift the beam, and it took quite a few goes before it actually lifted,” she said.
“I think he only lifted it for a few millimetres or something for less than a second, and then they just yanked me out as hard as they could.
“That was when the pain was at its worst, with the blood rushing down my legs, it hadn't had any flow for a while, so that was just excruciating. Especially when they lifted me up the wee manhole they'd made, and the blood rushing down, I was going in and out of consciousness, it was awful.”
From there, she was rushed to a waiting ambulance and took a medical plane to hospital in Wellington, where the long rehabilitation began. As the days turned to weeks and months, she learned to leave her wheelchair behind.
“I first had to learn how to stand, so before that, I had to learn how to get my legs off the hospital bed, and that was excruciating,” she said.
“I'd need to sleep because it was so exhausting and that's when we went to the standing machine, and the walking machine, and that took a lot of time, a lot of effort, a lot of energy.”
Her hard work paid off and she was able to overcome a broken pelvis, several surgeries, and a long battle with chronic pain to return to a normal life.
She’s now married and has even been able to have two children.
“Things are pretty good now, I can't feel my right foot, so that just makes it a little bit difficult with walking sometimes,” she said.
“My muscles are pretty weak, just from the crush injury, and by the end of the day I'm pretty sore and stiff and sort of hobble my way to bed at night.
“[But] I'm at a point now where I don't think about the earthquake too much, I've got my husband, and my kids, and, yeah, mum life keeps you pretty busy.”
The memories only come back now around anniversaries or when tragic events like Pike River, or the Christchurch terror attacks, come into the news.
“When these things have happened, I know the hell that they're about to go through, and I don't wish that on anyone, and I don't wish for anyone to even try and understand what I've been through,” she said.
“I hope from my story and from some others, that they'd have hope that they might be able to get through it as well. Not over it, but get through it somewhat.”
Her strategy all along was to take one day at a time and now, 10 years later, those days have added up.
Transforming her life and overcoming the odds, to prove there can be life after disaster.