The Game Animal Council is furious at whoever it was that released illegal sika deer in north Taranaki.
Fifty deer were let out in the area in what's believed to be a protest against the use of 1080, a poison commonly used across New Zealand to kill pests.
The Department of Conservation (DoC) slammed it as "selfish and short-sighted" eco-terrorism, and a threat to New Zealand's goal of becoming predator-free by 2050. DoC also said the deer could spread tuberculosis.
Game Animal Council chairman Don Hammond says it's disappointing.
"Somebody has taken it on themselves to do something that hasn't really been thought through very well. It's pretty damn stupid really," he told Newshub.
Local anti-1080 protesters denied being behind the release. Chris Wilkes, the chairman of the 100 Percent Pure Taranaki conservation group, told RNZ it was more likely to be hunters that did it.
"I think it's more likely to be hunters who are interested in hunting them, than it would be people trying to make some kind of a weird point."
Mr Hammond says the hunting community is offering to help DoC destroy the deer if needed. Six have already been shot.
"What we do have access to is some extremely capable and talented hunters, particularly of sika deer, and that probably in the immediate term is the best offer of help we can make.
"I'm sure the department have the capacity to develop a proper response. We, as a hunting community, will contribute as and when is appropriate."
Federated Farmers condemned the release.
Anyone who has information about the deer release or window breaking is urged to contact the Department of Conservation or the police. Information can also be provided anonymously to Crimestoppers on 0800 555 111.