The name of the dead teenager was not released yesterday, as relatives out of the country were still to be contacted.
A homicide investigation was launched after the youth was stabbed in Exe St, near the intersection with Thames St, between 9.30pm and 9.45pm.
Police were on the scene quickly and attempted mouth-to-mouth resuscitation and CPR, assisted by a member of the public, before an ambulance arrived. Ambulance staff also unsuccessfully attempted to resuscitate the youth.
Detective Sergeant Malcolm Inglis, of Dunedin, who is overseeing the investigation, told a press conference yesterday afternoon it was a "tragic event", with two young people involved in such a violent confrontation.
Fortunately, there had been some witnesses and police had been able to make progress in their inquiries.
A youth was arrested about 1pm yesterday and charged with murder.
The two youths were known to each other but were not friends. They had both been out earlier in the night, going their separate ways, and happened to run into each other later in the evening, Det Sgt Inglis said.
They were not with other people when the incident happened.
Police were still looking for the weapon and wanted to hear from anyone who might have found a knife, of considerable size - possibly a hunting knife - in the Exe St or foreshore area.
Residents in the area were asked to check their properties. Police also wanted to hear from anyone who might have witnessed or heard the altercation.
Det Sgt Inglis would not say how many times the youth was stabbed. It was not yet known if alcohol was involved, he said.
The youth's body was removed from the scene by hearse at 5pm yesterday. An autopsy will be carried out in Christchurch.
Obviously, there were some "very distraught" parents, Det Sgt Inglis said.
The scene, including the southern end of Exe St, was cordoned off and the cordon will probably remain until about noon today.
About 15 police officers were working on the investigation yesterday, including five from Dunedin. Police and Victim Support were supporting the dead youth's family.
There was a young man "shaking, screaming and freaking out" and he had blood on his hand, Mr Caldwell said. The youth tried to "barge in", but Mr Caldwell, who had never met him before, told him to get out of the house.
Mr Caldwell said he was shocked at the stabbing. "It's Oamaru; we're not America."
His neighbour had seen the youth's body and said it was the "worst thing he had seen in his life".
Alfonzo Fehui (18) said he had known the murder-accused since they were at school and he had been with him earlier on Thursday. He said he received a call from the youth that night and he was crying.
A man who lived opposite where the stabbing occurred said he heard nothing until he was woken by "banging and crashing" about 3am, when the cordon was being erected.
