A high school party in Remuera turned to chaos on Thursday night when a teenager allegedly attacked others on one of Auckland's most affluent streets. Only a trail of blood still leaves a clue to the dramatic night that left two young people in hospital. 

The scene of a teen party gone wrong was quiet this morning - but blood still spattered the footpath of the leafy, mansion-lined street. 

It stretched some 50m along the footpath in Remuera in central Auckland, and a patch of grass was soaked in what also appeared to be blood. 

It's all that remains of the drama that unfolded on Thursday night, when emergency services flooded the area after an assault was reported around 10.30pm. 

Neighbours have described police cars filling the street, a helicopter circling overhead, and teenagers detained late into the night. 

One neighbour said he heard people repeatedly yelling "why, why, why" in a hysterical tone in the aftermath of the incident. 

St John sent five vehicles to the incident including two ambulances, which took two seriously injured teenagers to Auckland City Hospital. 

An Auckland DHB spokesperson said one remained in a serious condition this morning and the second was stable. 

Police said they had taken two people into custody, and charged one with wounding with intent to cause grievous bodily harm. 

One of several trails of blood at the scene outside a teen party which turned violent on Thursday. Photo / Adam Pearse 

That person was due to appear in the Auckland Youth Court today, police said. The other was released without charge. 

Police have not confirmed whether the incident was related to a party. 

But several people close to the incident have told the Herald the altercation happened between partygoers and another group who arrived in a vehicle, and was linked to two schools. 

Neither school has confirmed to the Herald whether their students were involved. 

Houses on the street sport swimming pools, tennis courts and elaborately landscaped gardens. The house where the party is believed to have been held is valued at more than $8 million. 

The trail of blood is some distance from that house, though one neighbour understood the altercation had happened outside the property. 

One resident said he saw at least 25 young people - seemingly intoxicated - walking around the area about 8.30pm on Thursday. 

He said it was clear they had been drinking as bottles had been found later in the grass outside. 

Another neighbour, who knew someone close to the incident, said partygoers were still in shock. 

Dried blood on a strip of grass near where a party turned violent in an opulent Auckland street on Thursday night. Photo / Adam Pearse 

She believed the incident may have had something to do with the rivalry between the two schools. 

She had first heard a helicopter circling the area at 10.49pm, and 10 minutes later the street was filled with police cars. 

At 11.30pm, she understood people who were at the party had been kept at the property and were being questioned by police. 

This morning the woman was surprised to find what looked to be blood still evident on the footpath and grass berm. 

"I was a bit blown away that there's still blood there … they haven't even washed it down," she said. 

"I was thinking surely that should've gone by now." 

The woman - who had moved to Auckland from the regions - commented on how often crime was occurring in Auckland and how it made her want to leave the city. 

She felt the incident could be one of many that was linked to the after-effects of Covid-19 and how social restrictions had affected young people in particular - a comment also made by others in the neighbourhood. 

"We've always said the teenagers, the partying years and the ones [going] overseas, they got locked down for two years."