TORONTO (June 17, 2012)—A British man died in the collapse of a massive stage hours before a Radiohead concert in Toronto, police said.

Toronto Police spokesman Tony Vella said Sunday the man, who was in his mid-30s, was trapped under the rubble.

He was pronounced dead at the scene.

Vella could not provide further information about his identity.

Three others were injured when the top portion of the stage collapsed as the crew was setting up Saturday in Downsview Park.

Vella said a 45-year-old man hospitalized with a head injury was improving and his life was not in danger.

The other two were treated at the scene.

Dusty Lalas, an employee with a Toronto radio station sponsoring the concert, says the structure suddenly caved in. Lalas says there was a loud crash and it sounded like sheet metal and lightning.

Another witness says security officials rushed to evacuate the area. Jaime Rivest says there were possibly 1,000 people there hours before Radiohead was to take the stage at 9:30 p.m.

Authorities say there will be an investigation to determine the cause of the collapse.

Radiohead tweeted the concert had been canceled "due to unforeseen circumstances." The band's website had listed the concert as being sold out, with 40,000 tickets sold.

It said tickets would be refunded.