The provincial Ministry of Labour remained tight-lipped Sunday on details surrounding a stage collapse at Downsview Park that killed a drum technician for Radiohead and forced the cancellation of a sold-out show.

A spokesperson for the British band identified the drum technician as Scott Johnson, 33, of Doncaster, England. Johnson also toured with another U.K. band Keane.

“He was a lovely man, always positive, supportive and funny; a highly skilled and valued member of our great road crew,” Radiohead wrote on its website. “We will miss him very much.”

As three inspectors and two engineers from the ministry scoured the scene Sunday, it remained unclear what caused the massive structure to crumble, crushing Johnson and injuring three others.

Johnson was pronounced dead at the scene after sustaining what police said was a “heavy, crushing injury.”

Ministry spokesperson Matt Blajer said the investigation is “fairly complex” but could not confirm the names of any involved companies.

Meanwhile, industry professionals are questioning the circumstances leading up to the fatal accident, which occurred on an otherwise bright and sunny day, with only light winds.

Preparing a stage involves several companies, including stage and roof builders — which can be contracted by the event promoter, in this case Live Nation — and lighting and sound firms, often provided by the band.

Stage and scaffolding builders hire and work in concert with a structural engineer, who assesses how much weight the roof can hold. The so-called “load factor” is then presented to the promoter, said Ted MacDonald, of Audio Visual Methods, a Toronto production equipment company.

Blajer told the Star stage blueprints signed and approved by a “professional engineer” have been provided to investigators.

On the day of the show, plans can sometimes go awry, with builders, the engineer and the promoter sometimes disputing just how much weight a roof can hold, said MacDonald, who has worked in the staging business for more than three decades.

“People get pretty pushy when they’re doing these events,” he added.

Indeed, a quick, high-pressure turnaround between the moment a band’s technical crew arrives at the venue and show time often leaves little room for structural modifications, if need be, as promoters rush to prepare the stage.

“It is normal for the act to arrive at the venue the morning of the show, set up their equipment and perform that same evening,” said Jim Brett, president of International Alliance Theatrical Stage Employees Local 58, which did not supply stage hands for the Radiohead concert.

In an industry without clearly-defined safety guidelines, last-minute modifications can be crucial.

“Those little changes can make all the difference,” said Mike Garl, co-chair of the technical standards council at PLASA, a U.S-based trade group that represents the stage installation industry.

“In some cases, it is not clear who’s going to say, ‘That’s not OK,’ or ‘That doesn’t meet the standard’,” added Janet Sellery, an event safety consultant who advised at the 2010 Vancouver Winter Olympics. “I think there’s a lot of performances and events that may go on with a lot of fingers crossed.”

Several firms believed to be involved in the Radiohead stage construction could not be reached Sunday. Downsview Park directed all questions to Live Nation, which did not respond to requests for comment.

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Police said another victim, 45, remained at Sunnybrook hospital with non-life-threatening injuries. Paramedics treated two other men for minor injuries at the scene.

Roughly 40,000 fans were expected to attend Saturday’s concert, Radiohead’s first in Toronto since 2008.

With files from The Canadian Press