Authorities are investigating how a building site's roof collapsed at Perth's Curtin University, causing an apprentice construction worker to fall to his death.
The 23-year-old man and another worker fell more than 20 metres when a metal structure supporting the glass roof collapsed yesterday.
The second man was seriously injured and was undergoing surgery at Royal Perth Hospital.
Police and emergency crews were preparing last night to make the construction site safe so they could retrieve the body.
"A lot of the workers have stayed behind and obviously they'll be spoken to in due course to determine exactly what happened," WA Police Commander Mike Bell said.
"It'll be up to the engineer to declare it safe at which point we can then go in and remove the body of the deceased and start our investigation."
The building will house Curtin's new architecture school. Head contractor Lend Lease has not responded to requests for comment.
A third worker inside the building at the university's Bentley campus was also injured after falling about 10 metres.
Police said he was conscious and able to speak. Both injured men are in their 20s.
WorkSafe is also investigating the incident and a police report will be prepared for the coroner.
Electrical Trades Union WA organiser Damian Clancey witnessed the collapse and said it happened during the lunch break.
He said there could have been many more deaths and injuries had it happened just five minutes earlier.
CFMEU state secretary Mick Buchan said he had been made aware after the incident of there being issues with "deflection in the structural steel".
"Those issues were addressed by structural engineers ... (but) I understand that there were some concerns," he said.
"It's 2020. These events should not occur in the building and construction industry."
Construction began in 2019 and was due to be completed next year.