"We understand the serious responsibility that we have, along with all platforms, to effectively address harmful content and we want to reiterate that the safety of our users is our utmost priority," he said.
"This content is both distressing and a clear violation of our community guidelines and we have acted quickly and aggressively to detect and remove videos, and take action against accounts responsible for re-posting the content, through a mix of machine learning models and human moderation teams."
Hunter said he shared the concern voiced by New Zealand authorities and the wider community that materials like this was being made and shared.
"We are working closely with local policymakers and relevant organisations to keep them informed," he said.
"We have also updated related hashtags to surface a public service announcement, with resources for where people can seek help and access our Safety Centre."
TikTok users had reported harmful content on the app and warned others against engaging in it, Hunter said.
The Mental Health Foundation's chief executive Shaun Robinson said the footage "puts vulnerable people at an extremely high risk of real harm," and it was a good time to check in with rangitahi on their social media use.
Netsafe offered resources to parents wanting to support their children who had been exposed to upsetting content, while Chief Censor David Shanks had attempted to contact the Chinese-based TikTok over his concerns.
Netsafe chief executive Martin Cocker, whose organisation is the lead agency for enforcing the Harmful Digital Communications Act, earlier told the Herald he'd seen a rise in complaints about content on TikTok as the platform grew in popularity.
"Netsafe now has an operational connection with the TikTok Trust and Safety Team and we can help New Zealanders with any issues they experience on their platform," he said.
Cocker said he's been fielding calls from multiple schools, with Netsafe helping them to prepare advisories to parents and caregivers.
There have been reports that the distressing TikTok clip has also been repackaged with innocuous content, so the platform should still be approached with caution.
Netsafe has also posted two advisories that could help parents grapple with the situation: "Understanding TikTok" and "Helping young people exposed to upsetting content," he said.
Meanwhile Facebook spokeswoman Gina Murphy said the original video was removed from Facebook on the day it was streamed, and the company have used automation technology to remove copies and uploads then.
"Our thoughts remain with [the victim's] family and friends during this difficult time," she said.
Facebook tightened rules around acceptable content and bolstered AI and human filters after the Christchurch mosque shootings were livestreamed, but resisted calls to disable the feature - in contrast to Google-owned YouTube, which turned off livestreaming for most mobile users.
Where to get help
If it is an emergency and you feel like you or someone else is at risk, call 111.
• Lifeline: 0800 543 354, available 24/7
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO), available 24/7
• Youth services: (06) 3555 906
• Youthline: 0800 376 633
• Kidsline: 0800 543 754, available 24/7
• Whatsup: 0800 942 8787, available 1pm to 11pm
• Depression helpline: 0800 111 757, available 24/7
• Rainbow Youth: (09) 376 4155
• Helpline: 1737
