Engineers appear no closer to knowing why a lighting rig above the stage collapsed at Toronto’s Downsview Park Saturday evening, hours before British rock band Radiohead was scheduled to perform.

The top part of the stage came crashing down around 4 p.m. Saturday as several people were on the stage setting up for the concert. A drum technician for the band, Scott Johnson, was killed, while a 45-year-old man was taken to hospital with non-life-threatening injuries.

Structural engineers surveyed the twisted wreckage from cherry pickers on Sunday. However, engineers have not been able to access the scene on foot, CTV Toronto’s Austin Delaney reported Monday.

Inspectors with the Ministry of Labour are also on the scene, Delaney reported, but did not speak to reporters Monday morning.

The early days of the investigation will include determining who owns and operates the material and equipment used to construct the stage, and who employs the workers who set it up.

Inspectors have asked concert promoter Live Nation to produce documents that will make that side of the probe more clear.

A safety consultant specializing in the arts told The Canadian Press Sunday that inconsistent labour and safety standards put stage hands and crew members at risk, as bands seek to put on ever-more complex shows.

"In some cases, it is not clear who's going to say, 'That's not OK,' or 'That doesn't meet the standard'," Janet Sellery told CP.

"I think there's a lot of performances and events that may go on with a lot of fingers crossed," she added.

Sellery also pointed out that safety regulations have not kept up with technological innovations that bands take advantage of to put on jaw-dropping shows.

"It's not something that there's a lot of political or bureaucratic energy behind," she said.

"Doing live performance and events has always been about pushing boundaries and I think that's a good thing, but you have to make sure... that the health and safety practices keep up with that."

On Sunday, Radiohead’s members released a statement saying they were “shattered” by the death of Johnson, who they hailed as a “highly skilled and valued member” of their road crew.

"He was a lovely man, always positive, supportive and funny," a message posted to the band’s website read. "We will miss him very much. Our thoughts and love are with Scott's family and all those close to him."

As many as 40,000 people were expected to attend the concert. While some fans had already begun to arrive at the venue when the incident occurred, none had been let into the concert area.

The concert was cancelled and all ticketholders are to receive a refund.

With files from The Canadian Press