INDIANAPOLIS » At least four people were killed and 40 injured when a stage collapsed Saturday night during a storm at the Indiana State Fair, where the country group Sugarland was set to perform.

The incident at the Indianapolis fairgrounds occurred shortly before 9 p.m. when strong winds caused the rigging that holds lights and other equipment to topple onto fans, many of them in the VIP section closest to the stage. The injured included at least one child, WTHR reported.

No one was performing at the time. Opening act Sara Bareilles had finished, and the crowd was waiting for Sugarland to take the stage.

Hundreds of concert-goers rushed to tend to the injured, lifting the steel scaffolding off them and providing medical care. Emergency crews set up a triage center in a tunnel below the grandstand.

Witnesses reported seeing many people with head and neck injuries and broken bones.

Indiana State Police Sgt. Rich Myers confirmed the deaths and number of injured and said the injuries ranged from "slight to very critical." He did not offer any additional details.

Wishard Memorial Hospital spokesman Todd Harper said the hospital had 16 patients, none of whom had life-threatening injuries. Harper told WTHR the hospital’s youngest patient was 7 years old.

Concert-goers said an announcer had alerted them that severe weather was possible and gave instructions on what to do if an evacuation was necessary. But the same announcer said concert organizers hoped the show would go on, and many fans stayed put.

The wind that toppled the rigging came just minutes after the announcement, fans said.

"It was like it was in slow motion," concert-goer Amy Weathers told the Indianapolis Star. "You couldn’t believe it was actually happening."

Associated Press photographer Darron Cummings was in the audience attending the concert as a fan shortly before the collapse. He said he and his friends sought shelter in a nearby barn after seeing the weather radar.

"Then we heard screams. We heard people just come running," Cummings told the AP.

Witnesses told WTHR that some of the injured were in a VIP section in front of the stage known as the "Sugar Pit." The witnesses said a wall of dirt, dust, rain and wind came up the main thoroughfare of the fairgrounds just before the collapse.

"Panic kicked in when they seen the dust bowl coming in from the Midway," concert-goer Darryl Cox told the television station.

Another person at the concert, Emily Davis, told the station that there was lightning and the sky had gotten dark but it wasn’t raining when the wind suddenly toppled the rigging.

"It was horrible, people were running and going crazy," she said.

Jessica Alsman told the AP the towering, metal stage scaffolding "kind of wobbled at first." Then pandemonium set in as it fell.

"As soon as we saw the wind gust, the wind was in our faces," Alsman said. She said and three friends grabbed each other and formed a chain.

"You can’t imagine — we just thought it was going to rain or something," Alsman said.

Sugarland tweeted about the incident about an hour after it happened.

"We are all right. We are praying for our fans, and the people of Indianapolis. We hope you’ll join us. They need your strength," the band said.