HASSELT, Belgium - A storm swept through an open-air music festival yesterday, killing at least three people and injuring 71, an official said.

Concertgoers described scenes of panic as the sky darkened, winds whipped, rain poured, hailstones pelted the crowds, and concert structures buckled.

“It was frightening. It looked terrible. All the structures collapsed,’’ said Brinnie Gardner, 20, of Auckland, New Zealand.

Hugo Simons, Hasselt’s head of emergency medical planning, told VRT radio three people died, 11 were severely injured, and 60 had light injuries.

Organizers estimated that 60,000 people were at the three-day festival.

Video showed stage equipment dangling in high winds as rain-soaked concertgoers ran for cover. Trees all around the area were downed.

Laura Elegeert, 17, of Saint-Nicolas, Belgium, watched a tent collapse. “It was utter confusion, mass panic,’’ Elegeert said. People were trying to get out of the tent “by using their pocket knives and cutting holes in the fabric.’’

The festival’s lineup featured internationally known acts, including the Foo Fighters, Eminem, and The Offspring.

It was the second deadly event at a festival in a week. On Saturday, parts of a stage collapsed at the Indiana State Fair, killing five people and injuring dozens when winds of up to 60 to 70 miles per hour hit.

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