Up to seven people have died from taking synthetic cannabis in Auckland over the past month, prompting police to issue a desperate warning for people to stay away from the drug.
This week ambulance officers have been responding to up to 23 incidents a day, St John Ambulance medical director Tony Smith says, with the patients ranging from teenagers to middle-age.
"Patients under the influence of this drug are exhibiting grossly disturbed behaviour and/or suffering seizures," says Mr Smith.
"Most concerning is that the drug appears to be linked to some people's heart stopping beating and we have had seen seven sudden and unexpected deaths."
Mr Smith says patients often act abusive or threatening towards ambulance officers, "if these patients are lucky enough to wake up."
Police are investigating the deaths, and doctors at Auckland Hospital have been called to a crisis meeting on the matter.
"We as a community need to work together to stop this drug before another life is taken," says Detective Inspector Lendrum.
"We have grave concerns as users don't know what poisonous chemicals they are potentially putting into their bodies when they're smoking this drug."
Auckland District Health Board chief medical officer Margaret Wilsher says when people consider taking the drug, they should ask themselves: "Are you prepared to put your life at stake? Are you prepared to end up in hospital?"
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There is a possibility some of the products being sold could be laced with unknown chemicals.
Police say it is not an issue unique to Auckland, with concerns for communities New Zealand-wide, so the total number affected "could be even higher".
CCTV footage released by police show the harmful side-effects, with a man violently ill and unable to stand after smoking the drug.
Twelve people have been arrested in Avondale over the past few months for having the illegal substance.
Any information can be reported to your local Police station or anonymously via Crimestoppers on 0800 555 111.