"Critical" incidents included death, serious injury requiring hospitalisation, bomb threats and arson.
"Serious" incidents included physical harm requiring medical treatment, threats made with an intention to harm, stalking or intimidation of staff.
"Moderate" incidents included assaults where there was no injury, aggression and abuse.
"Minor" incidents were all other incidents that impacted the safety of staff and clients, or impacted the physical security of ministry assets, information or data.
From 2015 to 2017, police were involved in 60 security incidents at the Wanganui Service Centre Work and Income branch.
MSD stated that this didn't necessarily mean police physically attended the branch.
Whanganui Area Commander Inspector Nigel Allan said police do receive calls for service to Work and Income offices in all parts of the country – including Whanganui - for a variety of reasons.
"Police will treat all calls for service from Work and Income and other government departments seriously and we are committed to maintaining the safety of staff and members of the public," he said.
It's a system that has been built to dehumanise people... it doesn't take account of varied needs and it's simply not welcoming
Deputy Chief Executive at Ministry of Social Development Stephen Crombie said safety of their staff and clients is the absolute priority.
"Our zero tolerance for people who demonstrate threatening and abusive behaviour towards our staff and clients means that some incidents that may not have been recorded in the past now are," he said.
"Additionally, some threats and incidents that previously may have been considered to represent a minor risk are now interpreted in context of the potential worst case outcome, resulting in a rise in reported security incidents, and more definitive actions being taken.
"This is shown in an increase in incidents across the country, including Whanganui," Crombie said.
Work and Income staff had, on average, 540 face-to-face meetings with people who need their help in Whanganui every week, he said.
Whanganui was one of five sites to have an enhanced security design, which was introduced in February 2017.
PSA union National Secretary Erin Polaczuk said their members at Work and Income service centres frequently deal with clients who have high and complex needs.
"Like other frontline public service workers, they are trained to manage tense situations, but sometimes frustrations can boil over," Polaczuk said.
She said the PSA encouraged a zero-tolerance approach to these incidents.
"The PSA frequently discusses security issues with all state sector agencies, particularly those where our members deliver frontline services."
Executive officer of social service Jigsaw Whanganui Tim Metcalfe said the lack of privacy in the waiting room is a driver behind the incidents.
"We've got one building now, where people go in for all these different things, you might be an old person going in for superannuation, you might be a young person going into the youth service, you might be a single parent or you might be a job seeker - all waiting in the same waiting room," Metcalfe said.
The long periods of time people often have to wait to see a staff member is another factor that causes frustration and agitation, he said.
"What we have noticed, however, is that Work and Income staff are making a better effort with people that are waiting, so they'll have a couple of staff who are moving around who will make sure people get into the right queue," Metcalfe said.
Metcalfe said he believes the increase in the number of incidents was because people were battling a system and culture that disrespects people and puts them down.
"Everything is all on the computer and the computer decides whether you fit this box or whether you don't, it's a system that has been designed to exclude, or to say 'that's not our problem' or 'you don't fit in this box'", Metcalfe said.
He said some of it is just the frustration of waiting in queue after queue.
"The biggest issue I see is, it's a system that has been built to dehumanise people, it's mechanistic, it doesn't take account of varied needs and it's simply not welcoming. It's not saying 'you're important and we respect your mana and dignity'," Metcalfe said.
Metcalfe said he knows a number of Work and Income staff and a number of the managers.
"Our local staff are doing their best but they're working in a system that has actually been designed to disrespect and put people down and it's very evident when I go over there."
He believes the biggest and only protection against the rising rate of incidents is changing the culture, into one that treats people with respect and dignity.
"Otherwise we become a state like Donald Trump, the bigger the walls you put up, the more unsafe people become," he said.
"That's my big fear - that New Zealand is being turned into a state where people don't count."
Jigsaw works with around 700 families in Whanganui every year.
