A singer supporting New Zealand band Six60 warned people standing on a balcony to get off it hours before it collapsed, injuring 18 people.
Greta Bull, who performs as Re-Greta-Bull, said she had warned partygoers at the Dunedin concert on Friday that the balcony was unsafe after she noticed it going "up and down".
"Their reaction was good, a couple of guys took it really seriously and got everyone to jump off," she told Fairfax.
Despite her warning, however, students began to fill the balcony again.
"The other balconies seemed to have just as many people but they weren't moving anywhere near as much," she said. "It is just unfortunate . . . those balconies weren't safe enough to hold 20 people."
Police have decided not to launch a criminal investigation into the Castle St balcony collapse.
The police decision has been followed by a claim no one was jumping on the balcony, despite conflicting reports that people were.
Animation Research chief executive Ian Taylor said a 3D video his company was filming shows no one jumping at the time of the collapse.
The video shows footage 15 minutes before the balcony collapses but Mr Taylor said people were on the balcony for about three hours before, meaning people could well have been jumping earlier.
Meanwhile, Dunedin Mayor Dave Cull said the collapse must lead to an overhaul in how private events are run in the student quarter to avoid another tragic incident.
"The kind of event that happened on Friday night cannot happen again."
In another development, the Government launched an investigation yesterday into the collapse.
Two people remain in hospital. A University of Otago student, from Southland, whose back was broken in three places, has been transferred to Christchurch Hospital.
A man is in Dunedin Hospital in a stable condition in a high dependency unit.
Police Area Commander Jason Guthrie said police had done "due diligence on the information gathered to date and at this stage there is nothing to suggest any criminal aspect to this incident".
"On that basis there is currently no intention by police to investigate further from a criminal point of view."
"Police will, however, work collaboratively with Ministry of Business, Innovation and Employment and WorkSafe to support any investigations these organisations undertake."
Only one person was arrested at the concert - a 19-year-old Dunedin man for disorderly behaviour, who was later released with a pre-charge warning.
Speaking on TVNZ's Breakfast today, Prime Minister John Key said the inquiry was more about accountability and looking at wider issues around responsibility than looking at building standards.
"In the end you've got two people with serious injuries. It's not impossible you'd have deaths in a situation like this," he told TVNZ.
"There'd be a lot of parents who would be saying I want to understand who's accountable here."
Mr Key said there hadn't been enough discussion in Cabinet to decide whether the inquiry would look at whether building standards were robust enough.
WorkSafe New Zealand has yet to decide whether it will carry out its own investigation into the collapse.
A spokeswoman said: "We have to decide whether the circumstances of the incident meet the threshold for a WorkSafe investigation."
She said a decision was expected to be made soon.
Mr Guthrie said police would, as a matter of standard practice, debrief following the incident.
"Based on the information available to date, it is apparent that the police officers present, along with Campus Watch and emergency service partners have done an outstanding job of responding to what was a very challenging incident.
"I am very proud of my officers and commend them for their professionalism and sound use of judgment."
Police strongly recommended that "pop up gatherings promoted via social media" be avoided.
"This incident is an example of how well intentioned events can go wrong if not well planned and organised - from a crowd safety point of view."
Police liaised with the band on the night and the band co-operated with their efforts to keep the crowd safe following the collapse of the balcony.
Police would discuss with Six60 how the event was run.
"In due course police will seek to discuss the concert and the way in which it was organised and promoted."
Police had "no involvement whatsoever" in organising the event and were not given prior notification of it, he said.
- Additional reporting Otago Daily Times