The main stage at the site of the Big Valley Jamboree in Camrose, Alta., lies in ruins after a storm on Saturday. ((John Ulan/Canadian Press))

One person is dead and several others were critically injured after a storm knocked down the main stage Saturday at the Big Valley Jamboree near Camrose, Alta., about 95 kilometres southeast of Edmonton.

Witnesses said severe winds caused the stage to break apart, with parts of it collapsing on concertgoers.

Camrose police confirm that one person was killed and 15 others were transported to hospital. They said four people suffered critical injuries.

Numerous emergency vehicles rushed to the scene.

Strong winds, heavy rain and hail battered the jamboree, where thousands had gathered for the annual four-day event, said Camrose police Chief Darrell Kambeitz.

"The concert … was delayed and the concert bowl was being cleared when a small portion of the main stage collapsed," Kambeitz told The Canadian Press.

He added that decisions regarding the continuation of the jamboree on Sunday — the event's final day — would be made at a later time.

Vancouver-based country music singer Jessie Farrell, who had performed earlier in the day, said being there was a terrifying experience.

"It felt like bombs were going off around us in this concrete and steel building," she told CTV News. "Huge hits of power hitting the building, and then the lights were off."

She said that people were missing and trying to find each other, and "there was a woman who was trying to tell everyone to stop panicking and she was panicking on the speakers."

Police asked that concertgoers, who had pitched tents and parked RVs at the festival's 6,000 camping sites, stay put until the weather cleared to avoid traffic snarls.

Kambeitz said early reports that dozens of people were trapped under the stage were not true and that emergency crews quickly had the situation in hand.

Nashville musician Billy Currington and his band were onstage when the structure collapsed. Hollywood actor Kevin Costner and his band Modern West were scheduled to take the stage next, according to the Big Valley Jamboree website.

With files from The Canadian Press