The earlier one involved a school.
"In the case of that school shooter, like so many other individuals that we see overseas, he was also an avid consumer of extremist material. It's unclear exactly what was driving his behaviour. In each case, we received one report to indicate something was amiss."
'Copycat' risk
Auckland University terrorism expert Dr Chris Wilson, who was also on the panel, said the chances of another mass shooting in New Zealand were now much higher because of the risk of copycat attacks.
"The more dramatic it is and sadly the more casualties there are, the more likely it is that you will see that kind of contagion effect, the greater the numbers and the longer it will last."
Wilson said 500 copycat attacks over five years followed the 1999 Columbine School massacre in the United States.
"Traumatic events, for people who are suffering from mental illness or some form of psychological disturbance, often has a major impact on them and we often talk in the study of radicalisation about the combination of personal and political grievance.
"So, they might be going through some form of personal crisis, and all of a sudden they see a political cause that they can become part of."
The conference heard today that a lone actor using a vehicle, a knife or a gun remained the biggest terrorism threat in Aotearoa.
The SIS was drawing up a list of behaviours that family, friends and workmates could look out for in those they suspected of being radicalised online who might pose a risk.
Community information critical - Little
Security Intelligence Minister Andrew Little, who was also in charge of the response to the March 15 attacks, said information from the public remained their best tool in preventing a similar attack from happening.
"It has to be a community response too. So those things that drive people into being willing to accept radicalisation and buying into violent extremist rhetoric online, actually, it's the environments they live in, the communities they live in, the households they live in, and what we're doing there that is our best response to prevent [attacks] from happening."
A number of the bereaved, injured and witnesses to the March 15 attack were at the conference.
Ahmed Jahangir, who in September will undergo yet another round of surgery on his shoulder that was injured in the attack, said the conference showed the Government was committed to preventing a repeat.
However, he was disappointed that over the two days nobody from the Christchurch Muslim community was due to speak.
"And after what happened here in Christchurch. There are many, many Muslim leaders. We should have been on that panel, I believe. I was quite surprised to see there's no one from Christchurch ... who's speaking here."
Little said Muslim groups were consulted on the make-up of the various panels and victims were approached to see if they wished to attend the conference.
He noted the Hamilton-based Islamic Women's Council was hosting a session tomorrow called "What hate feels like now".
- RNZ