HASSELT, Belgium -- A storm swept through a popular open-air music festival in this eastern Belgium town Thursday, killing at least three people and injuring more than 70 others, an official said.

Ambulances and police cars raced to and from the site of the Pukkelpop festival, near the town of Hasselt, 50 miles east of Brussels, late Thursday, their sirens blaring. Concertgoers described scenes of panic as the sky darkened, the winds whipped, rain poured, hailstones nearly half an inch across pelted the crowds, and concert structures buckled.

"It was frightening. It looked terrible. All the structures collapsed," said Brinnie Gardner, 20, of Aukland, New Zealand, who is on a tour of Europe with a friend. "There was panic. It was crazy."

Hugo Simons, Hasselt's head of emergency medical planning, told VRT radio that three people had died, 11 had been severely injured and 60 had sustained light injuries as a result of the storm.

Organizers estimated that 60,000 people were at the three-day festival, which started Thursday, when the storm broke. Many were streaming out of the grounds after the storm, which turned the festival site into a scene of mud and destruction within about 10 minutes.

Video from the site showed stage equipment dangling in high winds as rain-soaked concertgoers at the music festival ran for cover. Trees and branches all around the area were downed, evidence of the sudden ferocity of the winds.

Ambulances ferried the seriously injured to nearby hospitals. Some of those lightly injured were being treated at a local sports complex. More than 20 ambulances were dispatched to the festival ground.

Images of the disaster showed fallen lighting scaffolds. Dutch NOS television reporter Rick Hoogkamp, who was attending the concert Thursday, said several tents collapsed. An AP reporter saw concession stands blown down and a large food tent spread across the ground.

One of those who watched a tent collapse was Laura Elegeert, 17, of Saint-Nicolas, Belgium.

"It was utter confusion, mass panic," Elegeert said. "People were trying to get out of this tent that collapsed by using their pocket knives and cutting holes in the fabric."

Two cranes were brought in to try to lift the large tent late Thursday, but the ground appeared too swamped for them to reach the area.

Chokri Mahassine, the organizer of the festival, said, "We have for now put the festival on hold until we understand the situation completely."

The three-day festival's lineup features internationally known acts, including Foo Fighters, Eminem and The Offspring.

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

Last month, a German woman died in a 100-foot fall from a tower at the Roskilde music festival in Denmark, but police said she likely committed suicide.

In 2000, nine people were crushed to death and 43 injured at the same festival during a Pearl Jam concert.

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Associated Press Writers Gabriele Steinhauser and Don Melvin in Brussels, and Toby Sterling in Amsterdam, contributed to this report.

Online:

Pukkelpop festival: http://www.pukkelpop.be/en/homepage