The raw images of the Christchurch mosque shootings on March 15 last year have seared themselves into the memory of Police Commissioner Mike Bush.
Fifty one people died in the attacks on the Al Noor and Linwood mosques in the South Island city.
"I've been a police officer for 42 years. I've never seen anything this horrific."
Bush had been sitting in his eighth-floor office at Police National Headquarters when, just after 1.41pm on March 15 last year, a call from the Canterbury District Commander informed him that a mass shooting was being unleashed on Christchurch.
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But hearing what was happening was not the same as watching a live stream when it was brought up on screen at the National Command Centre.
"What's stayed with me most are the images of how those people were suffering ... what they must have been going through," Bush told the Herald.
"Our worst fears were realised - that innocent people going about their prayers were being attacked in their place of worship.
"And to watch it almost in real-time had an impact on everyone in that room."
As head of police, Bush had a job to do - but he is also human.
"You can't prevent yourself from being affected by what you're seeing, by seeing the trauma that these people were going through. Police officers have a habit of burying their emotions deeply, but we are human.
"At the same time, you must remove yourself from being driven by emotion and ensure that your actions are absolutely professional and clinical. That's what's required of whoever takes charge of such an incident ... so that our decisions, which have such significant impact, are the right decisions."
Those images also hit home how important it was for the response teams to prevent any further harm to those worshippers, Bush said.
"I will never be more proud of police and emergency services as to how they put their lives on the line to save and help others in their absolute time of need."
Six minutes after the first 111 calls and seven minutes after the first shots were fired, the first police officers arrived at the Masjid Al Noor on Deans Ave. They did not know how many gunmen there might be or if any were still at the scene.
Ten minutes later, Senior Constable Jim Manning and Senior Constable Scott Carmody were driving on Brougham St when they saw a car with a plate that matched the one on the alleged gunman's live stream.
They rammed the car off the road and dragged the alleged gunman from the car. The arrest took place about 18 minutes after the first shots were fired.
"They had the experience and sense to know how to go about bringing this to a safe conclusion, but that took absolute courage," Bush said.
But they weren't the only emergency staff confronting a situation with many unknowns; ambulance staff entering into Masjid Al Noor, for example, were stepping over casualties and blood-stained tiles.
"There were other officers going into those scenes not knowing what was in front of them. To put yourself in that position for others is what our people come to work to do, and I can't speak more highly of them."
Bush said he was very aware of needing to tell the public what police knew, as well as what they didn't know. Police provided regular media updates, and Bush gave a press conference at 5pm.
"We weren't clear at that point how many people may have been involved. And we didn't know whether this was an incident isolated to those locations or whether it was a lot wider.
"So we were trying to make sense out of chaos. And in doing that, we wanted to make sure every New Zealander took care of themselves and was really vigilant about themselves and their families."
Bush said the way New Zealanders responded in the days following the shootings - with love, compassion and inclusion - was part of the national identity.
"It didn't matter where you were in the country, everyone was doing what they could to put their arms around the Muslim community.
"I was in Kilbirnie at the mosque [two days after the shootings] and it was four deep, five deep, not around the mosque, but around the entire block.
"It was a fantastic display of how New Zealanders really feel about each other. And I encourage everyone to never lose that. That's what makes New Zealand special."
Bush only has a few more weeks until he comes to the end of his term as commissioner, and hopes that the vigilance that followed the attack will persist, noting the increase in reports about suspicious activity following March 15.
"It's really important that that vigilance is maintained so that we can work together to prevent any such incident from ever occurring again.
"I can tell you that everyone in police, everyone in the security agencies and other similar organisations come to work every day to prevent something like this ever occurring again, and that stays at the forefront of our minds."
Like many who were put to the test last year, Bush said that March 15 "will stay with me obviously forever, like it will in so many people's minds and memories".
"It's probably changed all of us. We saw things we never want to see again and it made me particularly more determined to ensure that everything our organisation does is about preventing harm in the community ... knowing what the consequences could look like if we don't get it right."
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Whats Up?: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
If it is an emergency and you feel like you or someone else is at risk, call 111.