When I first heard on Saturday about the killing in the Christchurch suburb of Sockburn, I made the assumption that it probably involved people who knew each other.
I think that's because we've been so conditioned in recent years to think that. Because of the stats that get thrown around all the time about the high percentage of people who are murdered knowing those responsible.
So come yesterday, and seeing the news that the killing on Saturday was completely random, I was horrified.
Here was a woman who'd been at work on Saturday, finished up, got the bus home, had a 300 metre walk from the bus stop to her house, was nearly there - it was about 20-past-four - but she didn't make it home. She was attacked in broad daylight by a man with a knife. Emergency services got there, but they couldn't save her and she died at the scene.
People who knew her are saying she was kind, supportive and a lovely community mum.
The police are saying the man allegedly responsible for the killing was known to them. It's also being reported that he was in the care of mental health services.
It seems he was arrested pretty shortly after the incident - he was nearby and was with his brother who was also arrested but released later in the piece.
The police have been saying since they arrested the man that they're not seeking anyone else in relation to the killing. Which is police-speak for "no one else was involved, so don't panic thinking there might be someone else out there".
Which is a good thing. But I do think people will be thinking twice. And, if they're not, they should be. I should be. You should be. Because while, technically, what happened on Saturday was a random, isolated incident - it doesn't mean it can't happen again.
It's happened before. It was only on Thursday that we had that guy stabbing people on the North Shore in Auckland. There was the attack on shoppers at the Countdown supermarket in Dunedin too, wasn't there?
And now it's Christchurch's turn. And this time it's a woman in her 50s walking home after work on Saturday in Sockburn.
But let's not forget either the people living in the area where this terrible thing happened. As one of them told the NZ Herald - "It's really upsetting. Just the worst thing to happen in your street."
Especially for the residents who saw what was going on and who helped her while the emergency services were on their way. You never hear much about these people in cases like this, but they will be so traumatised by it all.
And, as it always does after something like this, the world feels less safe.
Under that beautiful blue sky we had on Saturday, I was getting sheets off the line when it happened. It was nearly 4.30 - you might have still been out in the garden. Or out for a walk or a run or a bike ride. Or out having a drink with friends in the last of the winter sun.
But under that same beautiful sky, this poor woman's life was being ended in a suburban street by someone she didn't know from a bar of soap, armed with a knife. It is chilling, isn't it?