It was an atrocity the impact of which was felt around the country and, one year on, it is around the country the Christchurch mosque attacks will be remembered this week.
A national service is planned in Christchurch on March 15, with more planned in other centres through the week.
The National Remembrance Service, Ko Tātou, Tātou We Are One, is to "remember and honour those who died and build on the spirit of unity that came out of the tragedy", Christchurch City Council says.
It will take place in Christchurch's North Hagley Park from 3pm and include music from Burnside and Cashmere high schools - both lost pupils in the attacks.
Muslim leaders and Mayor Lianne Dalziel will also take part in the service, jointly led by Christchurch's Muslim community and city council, the Government and Ngāi Tūāhuriri as mana whenua, the council says.
The full order of service, including live-streaming details, will be announced this week.
The programme involves input from those most affected by the attacks, including survivors and families of those who died, the council says.
Last week, some members of the Muslim community expressed displeasure, saying the service contradicted Islamic culture , which doesn't typically mark anniversaries.
But Al Noor Masjid imam Gamal Fouda this week said the events of March 15 were a "crime against humanity" and deserved to be treated as an exception to normal Islamic rules.
Christchurch massacre survivor Farid Ahmed pens book, donates all royalties to St John
Christchurch mosque shooting: Survivors front up to pre-trial court hearing
Peace man: Christchurch mosque survivor Farid Ahmed honoured with award
The memorial is an opportunity for New Zealanders to stand together against hate and hate speech, Fouda says.
Meanwhile, police have already increased patrols around Al Noor and Linwood mosques, and on Thursday searched an address in relation to a threat against Al Noor mosque. A man was charged on an unrelated matter as police continued to gather evidence in relation to the Al Noor incident.
• The Conversation: Christchurch terror attacks prompt rise in extremists views
• 'Terror attacks strike at our hearts in the same way': Jacinda Ardern sends thoughts to London
• London Bridge terror attack: How ordinary people became heroes
• Terror in London: Man shot dead after stabbing attack
Security measures for the National Remembrance Service are under wraps for "operational reasons", police say.
At the national service two weeks after the shootings, snipers, armed police, specialist units and undercover officers were on high alert.
In Auckland, gates open from 2pm at Eden Park for the Stronger Together remembrance event, with a live cross to Christchurch's national service an hour later, followed by Auckland's own remembrance event at 4.30pm.
Central Auckland's St Matthew-in-the-City, in partnership with Al-Masjid Al-Jamie Ponsonby Mosque, will host a vigil including prayers, candles and silence between 5pm and 6pm on March 14. Free parking is available in a Wilson carpark next to the church.
Several events are also planned in Wellington, including the Federation of Islamic Associations of New Zealand-organised Umah Day Exhibition, which will show the Islam way of life at TSB Auditorium between 10am and 4pm on March 15. Kilbirnie Mosque will also hold an open day between 10am and 3pm on March 15.
Events are also planned in provincial cities, including a free Kotahitanga (togetherness) event organised by the Nelson Whakatu Muslim Association at Nelson's Trafalgar Centre between 6.30pm and 9pm on Tuesday.
In Napier, the Multicultural Association Hawke's Bay will, with the support local councils, host a 90-minute memorial from 5pm on March 14 at the Napier Soundshell, while Palmerston North residents can attend a multi-faith vigil from 7.30pm on March 15 at the Cathedral of the Holy Spirit.
The service will be jointly led by the Manawatu Muslim Association (MMA) and the Palmerston North Interfaith Group.
Civic events are not planned in some places, such as Hamilton, at the request of the city's Muslim community.