HASSELT, Belgium (AP) — Young people screamed and fled in panic as a fierce thunderstorm shredded huge canvas tents and brought down metal scaffolding at an open-air festival in Belgium, killing five people.

Hasselt Mayor Hilde Claes said Friday that two more people had died, bringing the toll from Thursday night's disaster to five. About 140 were injured in the storm, 10 of them seriously, she said. All the dead were Belgians.

Organizers canceled the annual Pukkelpop festival near Hasselt, 50 miles (80 kilometers) east of Brussels and sent the 60,000 festival goers home Friday in fleets of buses and trains.

The brief, violent thunderstorm toppled the poles of several concert tents and left them in tatters, flapping in the wind. It also downed several trees and the scaffolding for the main stage, where rows of concert lights swung wildly before crashing down.

Skin, the lead singer of Skunk Anansie, which was performing on the main stage when the storm hit, described the chaos on the band's Facebook page. She said "a burning hot sunny day turned into a mini-hurricane."

"(A) tower fell onto our truck, we had to run for our lives mid-set as hail hit the stage and the wind began to tear it to pieces," she wrote. "This was the scariest moment I have ever seen or felt in my 20 years of being an artist."

Video showed panicked concertgoers crawling out from under the downed tents and running through fields of mud looking for shelter.

"We were dancing away and it (the shelter) caved in in the middle and people were screaming and running away," one sodden young woman told Associated Press Television News.

Dr. Pascal Vranckx of Jessa Hospital in Hasselt said many of the injured were hit on the head by flying or falling debris.

"There are still three patients in critical condition, fighting for their lives," he told reporters.

After the storm, thousands of mud-splattered young people, many of them shoeless, trekked down the avenue from the festival to train and bus stations in Hasselt. Many had stayed on in the camping ground in the vain hope that performances would continue on Friday.

At a news conference Friday, Hasselt officials and festival organizers described weather conditions at the event's opening day as exceptional and said weather forecasters had not predicted a storm of that intensity.

The Belgian weather service refused to give the exact speed of the wind, saying only that the storm was "violent."

Chokri Mahassine, organizer of the annual festival that was first held in 1985, said he had never seen anything like it. "I have seen many tropical storms, but this was unprecedented," he told journalists.

"This is the blackest day that any Belgian festival has experienced," Mahassine said, adding he canceled the event "out of respect for the victims, their relatives and friends."

Belgian Prime Minister Yves Leterme offered condolences to the families of the victims and said authorities would continue to help caring for the injured.

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

"Our hearts go out to everyone affected by the tragic events at Pukkelpop," tweeted the Foo Fighters, whose Thursday night show was canceled after the storm hit.

"This is not how it should be. Oof," tweeted the Fleet Foxes, who had also been scheduled to play Thursday night. Earlier, the band used Twitter to assure their family and fans they and their crew were all safe.

Damien Poinen, an 18-year-old Belgian, was one of the many people who camped on the festival grounds overnight in the hope that the performances would continue.

"On the one side (canceling the festival) was the right thing to do. On the other side, some still wanted to party," he said. "Considering the people who died here yesterday, I was not going to stay anyway."

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 70 mph (112 kph) hit the site.