Two other people were also injured in the accident and are being assessed, 680News reports
The Globe & Mail added
the collapse "happened as stage equipment was being erected, but there was 'some kind of failure.'"
It's unclear if the fatality and injuries are related to workers or contractors at the concert.
Concert-goers already at Downsview Park are saying on Twitter that the area has been cleared by emergency crews, according to the Toronto Star.
One music lover isn't thinking too much about the cancelled Radiohead show he was about to see.
Toronto resident Jon Ophek, 31, a musician who plays in the motown band The Intentions
, said he thinks Radiohead fans should be thinking more about the family of the killed man and less about the cancelled show.
"This is incredibly tragic and it's sad to see when people react about the show," he says. "Someone died here."
As for tonight, Ophek has a solid plan B: the free Flaming Lips show at Yonge-Dundas Square, part of the North By Northeast festival
. "Not too bad, I get to see both shows in the end," Ophek says, but he has yet to learn when the rescheduled Radiohead show will take place.
Toronto hasn't been the easiest city for Radiohead to play. In 2009, lead singer Thom Yorke stopped
the show mid-song when a fan passed out. He then re-started the song when security gave him the all-clear.