Witnesses have described how a man with a knife has threatened numerous people in Christchurch, with one bystander saying the man was demanding "money, a wallet and phone".
Police responded to reports of a knife-wielding man who seriously injured a person in Christchurch this afternoon.
A man was taken into custody just before 6pm. No shots were fired.
In a statement tonight police confirmed a man had been arrested following a robbery and assault.
"About 4pm police received a report of a robbery on Ensors Rd, Waltham.
"A person had been threatened with a knife and their phone had been taken.
"A short time later, police received a second report of an assault on Isabella Place. A person had been stabbed and was seriously injured.
"Police located the man at a Mackenzie Courts address and he was taken into custody."
A 31-year-old man had been charged with four counts of aggravated robbery and one count of assaulting police.
He is due to appear in Christchurch District Court tomorrow.
A number of police remain at the scene and it is understood an investigation is ongoing.
A man claiming to be the alleged offender's brother said his brother had been recently released from prison and he is "scared of what might happen if his brother doesn't come out".
A video posted on social media showed a man in a blue T-shirt holding a knife and being spoken to by police officers near Ferry Rd, Waltham, around 4pm.
Police responded to reports of a robbery and an assault in Christchurch.
"About 4pm police received a report of a robbery on Ensors Rd, Waltham," a police statement said.
"A person had been threatened with a knife and their phone had been taken.
"A short time later, police received a second report of an assault at Isabella Place. A person had been stabbed and was seriously injured."
St John confirmed one person has been taken to hospital with serious injuries.
Police surrounded a house and shouted to the alleged offender: "You're not going anywhere, the house is surrounded, we know you're inside."
A woman at the scene said the man lived in a unit at the address and had been there for quite a while.
Witnesses said the alleged knifeman had earlier held up a teenager at a bus stop and demanded his cellphone.
A friend told the Herald the boy was scared and handed it over.
Others at the bus stop were also threatened. One woman said they were also approached at the bus stop and the man threatened them with a large knife.
He asked for a man's watch and put a knife to within 5-10cm of his chest.
"He held a knife to him," a woman said, relaying the incident.
But he refused to hand it over and the man ran off, into a nearby flat just 25m away.
The flat is now surrounded by armed police.
They're telling the man he is surrounded and he needs to come out.
Another bystander recalled how the teen was held up.
"He took one of the boys' phones," he said. "He was pretty scared so he gave it to him.
"I was going to throw a rock at him."
A witness who lives on Fredrick St said the man confronted his neighbour. He said she answered the door to a man with a knife.
"He just rocked up knocked on the door ... she had her baby on her hip," he said.
"He was completely unknown ... he demanded her money and wallet and phone.
"She started to scream and cry and that's the first we heard ... we ran out and it all unfolded."
A man who says he is the brother of the man at the centre of the incident is at the scene.
He told the Herald his older brother got out of prison recently and then spent time in Hillmorton Hospital for mental health issues, including schizophrenia.
"He's got mental health issues ... police won't solve anything," he said. "Only a doctor can help. Let me talk to him. I could sort this out ..."
He said police he'd approached refused to let him in.
"He's going down ... " he said. "He did years [in prison] ... for stabbing. Prison did this to him."
The man said he was scared of what might happen if his brother didn't come out.
"He'd rather die than come out ... he's going all out."
He told police he'd seen the fracas on Facebook and came down the street to try to talk his brother down.
Despite calls from a gathering crowd to let the man in police would not allow it.