The Dunedin party where a woman died was dangerously overcrowded with no room to move, a witness says.

A woman died and two people sustained serious injuries at the event, which took place at a Dundas St address and was broken up by police around midnight on Saturday.

The witness, who did not want to be named, told Newshub the house was so full she couldn't even make it inside when she arrived.

"It was incredibly crowded. It looked like there was probably 300+ people in the house.

"We got to the front door, some of my other friends went in, at this point we were being told to leave and so myself and two others we then went back to the side of the road."

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The witness said the house had recently been bought by the university and the party was being held as a final bash before it was handed over.

She said the inside of the house was dangerous.

"It was shoulder-to-shoulder, there was no wriggle room, if you fell over you weren't going to get up for a long time."

Outside the party, the witness saw three people believed to be occupants of the house come out in a distressed state and emergency services arrived soon after. 

"We had heard, kinda just through the grapevine, that someone had potentially jumped off something and snapped both of their legs and they were being crushed.

"One of my friends was actually stuck in a doorway, helping this person, but people weren't listening to her and wouldn't get off them. "

She said police cleared people out and the victim was brought out in a terrible state.

"The girl, I'm presuming is the one who passed away, she was carried out by four people and outside the front of the house, they were probably doing CPR on her for about 15 minutes before taking her onto an ambulance.

"Seeing her being wheeled away I could see the heart rate monitor and it was just a flat line so that was pretty awful to see."

For the partygoers assembled outside the house on the road, it was a "pretty awful" vibe, with attendees crying and distressed.

"It was such an awful sight to see, you know there was obviously a girl dying on the side of the road," the witness said.

Police are investigating what happened at the event and ask any attendees to get in touch. 

In a statement police said officers were called to the party to shut it down around midnight on Saturday. When officers arrived they found a number of people in the process of leaving the party, with reports of some people being injured as they did so.

Newshub has contacted Otago University for comment.