Three children under the age of ten are believed to be the victims found dead in a Timaru house and a woman in hospital is the suspected killer, the Otago Daily Times reports.
Before the three children were found dead, a neighbour heard a bang and then the sounds of sobbing and moaning at the Timaru house.
Police have launched a homicide investigation.
A fourth person was taken to hospital. The ODT understands the person taken to hospital is a woman and the suspected killer.
Jade Whaley lives next to where the incident took place and said that at about 9.40pm last night she and her husband heard banging, followed by sobbing and moaning.
"We went outside and realised it was coming from the neighbouring property."
There are three units on one side of the Whaley's property and while outside they saw a fellow neighbour speaking to a person at the back unit.
They later found out the neighbour called police, who arrived at 10pm.
"Everything got cordoned off. We weren't sure what had happened but we knew something significant had happened."
Later on, they saw a woman being supported while she walked into an ambulance.
She said they also saw a man in handcuffs taken away in a police car.
The units next door are often leased by the nearby hospital, Whaley said.
"They have staff that work at the hospital live there. Often people are there on short leases, three to six months.
"We think the people at the back flat were fairly new."
A hospital staffer told the Herald that while everyone was discussing what happened no one knew who was involved or the details.
He said a number of specialists and surgeons from overseas lived in the houses but he did not know who was occupying them currently.
Detective Inspector Scott Anderson said emergency services were called to the address shortly after 10pm last night.
"On arrival at the scene, emergency services found three deceased people. One other person has been hospitalised," Anderson said in a statement.
Police were speaking with people from the address and no one else was being sought.
"Police are still in the very early stages of this enquiry and no further information is available at this stage.
"If there are any cordons in place we would simply ask that residents follow the directions of officers, and we thank them for their cooperation."
Despite rumours around those who could have been involved, police say they are not in a position to comment.
Police are expected to front a press conference to provide an update on the investigation but a time has yet to be set.
Neighbours said they were not aware of any children living at the property but sometimes youngsters came to visit.
They believed the homicide happened in the back house on the property which is made up of three separate units.
The neighbour said tenants were usually very quiet and respectful and there was never any trouble.
She said last night she saw a woman taken away in an ambulance, and a man getting a police car.
She was not sure who they were and could not rule out the man was the neighbour that chanced upon the triple homicide and called 111.
A man connected to the owner of the unit politely declined to comment when approached by the Herald this morning.
The scene is cordoned off and the police forensic team arrived at the property at about 9.50am. A scene examination will get underway soon.
Timaru Mayor Nigel Bowen said the community will be devastated by the tragedy.
"Again, unfortunately. It seems that the community has had layers of tragedy with the five young lads that passed away so it's really tough," he said.
He said the area where the incident took place is "just a typical suburb" and relatively quiet.
"I think the community will be thinking, why is it happening to a place like ours?
"There's a lot of pressures on society at the moment, you have to question the support around mental health, are we doing things right in this country? I question that we're probably not."
A witness at the scene who did not want to be named said there was a lone police officer at the scene around 9am.
"They've given him a portaloo and he's got what looks like his lunch in his backpack beside him.
"He's just standing there all day as a site guard from what I understand. If it wasn't for that policeman standing there you wouldn't know anything had happened."
The scene is "just up the road" from the local hospital, they said, and patients are still coming and going as usual.
"I'm guessing that they did all that they had to do last night. Initially, pretty much everyone in town thought it was gang-related, it appears that might not be the case now but that was definitely the first line of response. Everyone is talking about it."
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• LIFELINE: 0800 543 354 or 09 5222 999 within Auckland (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633 ,free text 234 or email email@example.com or online chat.
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757
• SAMARITANS – 0800 726 666.