TORONTO - A massive stage collapse before a Radiohead concert at Toronto's Downsview Park has killed one person and injured several others, Toronto paramedics say.

No band members were believed to be on stage at the time of the collapse, but concert crew were working in the area at the time.

Radiohead cancelled their performance as a result.

"Due to unforeseen circumstances, the Radiohead show at Downsview Park tonight has been cancelled," the band said in a message on its website. "Fans are advised not to make their way to the venue."

The doors to the outdoor venue, which was to be filled with 40,000 people, were to open at 5 p.m. with opening act Caribou going on at 7:30.

On the packed subway heading north toward concert site, word began to spread the show was in jeopardy, then had been cancelled.

Those arriving at the last stop were greeted with an announcement that the show was "cancelled due to a police investigation" and encouraged to ride back into the city.

The mood of revelry - open drinking and singing Radiohead songs - on the way out to the park was subdued on the way back. Some on the train were heard hastily arranging to go instead to the free Flaming Lips show later Saturday night. That possibility took on added appeal after Flaming Lips frontman Wayne Coyne used Twitter to invite members of Radiohead and their crew to join them on stage.

There is also an unconfirmed report that Radiohead was scheduled to play a "secret" show at the Toronto bar Sneaky Dee's Saturday night.

The safety of stages at outdoor concerts has become a matter of increasing concern in recent years. A stage collapsed in high winds at the Bluesfest in Ottawa in 2011 while Cheap Trick was playing, injuring one person. At the Indiana State Fair last August, seven people were killed when high winds knocked down scaffolding and speakers. Last Saturday, the Electric Daisy Carnival in Las Vegas was shut down by windstorms, forcing the cancellation of a number of shows.

According to weather reports out of Toronto Saturday, the skies were clear, the weather was warm and there were only light winds.

Ottawa Citizen

With files from Andrew Potter