A female student has died at an out of control party in Dunedin overnight, where witnesses said a staircase collapsed.

Two other people suffered serious injuries.

 Ambulance and police were called to Dundas Street just before midnight after the occupants had called for assistance to shut down a party.

Police said when they arrived a large number of people were in the process of leaving the property and there were reports of people being injured as they did so. 

Vice-Chancellor of Otago University, Harlene Hayne said the University, which the deceased had attended, has been working with those affected and the police.

“We are deeply saddened by what occurred last night. We are supporting the family of the student who died. Many members of the student community are badly affected by what occurred last night.

"Our staff are working with them today, and will continue to do so, at this very difficult time,' Ms Hayne said. 

Kinnon Nelson was at the event, but left before the incident unfolded.

He told 1 NEWS "it was really crowded", estimating between 500 and 1000 party-goers.

"The whole stairway was all blocked and stuff. Just a massive mosh pit really, couldn't really move."

A cameraman behind the Dunedin-antics Facebook page was also at the scene and he heard that a staircase collapsed inside the building of the house party.

A spokesperson from Dunedin Hospital told 1 NEWS they treated some other people with minor injuries but none were admitted.

"It wasn't a significant number [of patients], and obviously they were minor injuries if they weren’t admitted," the spokesperson said.

Police said in a statement, "If you were at the party and have not spoken to police, we would ask you to please get in touch, to help us piece together what happened.

"Victim Support is available for those who were present."

Further inquiries are being made.