The Mental Health Foundation is rejecting the idea the man accused of carrying out the Christchurch terrorist attacks was mentally ill.
Organisation chief executive Shaun Robertson told TVNZ1's Breakfast the idea could be damaging to New Zealanders who do have mental health issues.
"This [attack] is about white extremism and white extremism is not a mental illness," he said.
"There is still a lot of stigma around mental health and sadly we see it all the time, and quite frequently in the news in New Zealand in the last year, an association between violent crime and mental health issues."
Mr Robertson said those ideas were "completely incorrect" and research showed people working on mental health issues were less likely to be involved with violent crimes.
"This assumption that people with a mental health issue, like myself, are somehow scary and dangerous and that we need to be controlled just pushes people more into that sense of shame and fear, not wanting to talk about their mental health.
"The issue here is what is the political indoctrination that this person [the alleged shooter] has been exposed to and has put themselves through."
As a nation, people's mental distress and wellbeing had been impacted, Mr Robertson said.
With emotions high throughout the country people should reach out to one another, hold onto routines, stop obsessive looking at news, exercise, eat well and try to sleep well, he advised.
"We're in shock. Obviously people close to the event or perhaps viewed that horrific streaming online could well be quite traumatised."