Police have revealed plans were uncovered for other potential mass shootings in 2019 - both before and after the March 15 mosque attack in Christchurch.
Cameron Bayly, the chief counter-terrorism advisor for police, made the revelations in Christchurch on Tuesday - at the first annual hui to combat terrorism. An annual counter-terrorism hui was one of 44 recommendations made by the Royal Commission of Inquiry into the mosque attacks.
Speaking at the hui, Bayly says police received vague reports from members of the public - one of which "stated intention to undertake a school shooting".
"On both occasions, the staff in question made a deliberate decision to look further just in case," he said in a speech.
Bayly spoke of two cases in the weeks before and after March 15 - where guns among other items of concern were found after reports from the public.
"Public reporting led us to individuals [with] firearms and other concerning equipment and, in one case, highly detailed plans - or at least a stated intention to undertake a school shooting.
"In the other case, individuals stated their intention to carry out a violent attack.
"These and other cases illustrate just how fine the line can be within the opportunity to intervene and having to respond.
"In both cases, many other steps had to be taken before we were able to get to grips with the threat and gain control of the situation."
The hui also heard the Christchurch gunman's manifesto is still circulating online and the tragedy could spark another attack. Security Intelligence Service (SIS) director-general Rebecca Kitteridge, in her speech, raised concerns people with different strains of extremism are now interacting in the same online spaces.
According to the Royal Commission report into the attacks, released late last year, Christchurch gunman Brenton Tarrant started using the online platform 4chan, often used for hate speech, from age 14. The Royal Commission believed exposure to such content contributed to his actions on March 15.
Kitteridge said reporting suspicious behaviour could save lives.
"Everybody has a role to play and we all need to understand what we can do, both individually and together, to oppose violent extremism in all its forms and to keep our communities safe."
SIS Minister Andrew Little noted the police can't be everywhere at once and the public had a role to play.
"If you see behaviours that are concerning that look like they are tending towards expressions of violence, then they should take the step of reporting that."
Earlier, Prime Minister Jacinda Ardern said the Government was listening and responding to the Royal Commission into the March 15 attacks.
Ardern addressed the hui via Zoom on Tuesday morning, after her flight was cancelled due to fog.
"Over the next two days, you'll have the opportunity to help shape a centre of excellence - helping form public discussion and guide the work of policy agencies across [the] Government."