Schadle could not immediately confirm the cause of the roof's collapse, but he said the National Weather Service informed officials of a tornado warning at 7:45 p.m. CT. The roof collapsed 10 minutes later, he said.

One person was killed and 28 others were injured after a roof collapse at the Apollo Theatre in Belvidere, Illinois, during a metal rock concert on Friday evening, officials said.

Around 260 people, including guests, performers and staff, were inside the venue that was hosting the heavy metal gig at the time of the collapse, Belvidere Fire Chief Shawn Schadle told reporters.

Schadle could not immediately confirm the cause of the roof's collapse, but he said the National Weather Service informed officials of a tornado warning at 7:45 p.m. CT. The roof collapsed 10 minutes later, he said.

Belvidere is in northern Illinois, roughly 14 miles outside Rockford city. Despite severe weather in the region, there were no reports of an “actual tornado” hitting the area, Schadle said.

Twenty-eight people were transported by ambulance to nearby hospitals, Schadle said, noting that five had severe injuries.  “Obviously there were probably other patients transported by personal vehicle,” he added.

Officers responding to the incident were greeted with “absolute chaos” inside the building, Belvidere Police Chief Shane Woodley said.

“It was a large response not only from all the public safety agencies, police, fire, as well as the bystanders to rescue those that were initially injured,” Schadle added.

Illinois Gov. JB Pritzker said he is “closely monitoring” the situation. “I’ve been in touch with officials for updates and to direct any available resources we can,” he tweeted Friday night. “As we learn more, please follow the guidance of all local authorities.”

Morbid Angel, one of the metal bands scheduled to perform at the event, issued a statement on Facebook cancelling the concert and urging fans to “seek shelter and stay safe”.

“We are currently sheltering in place, and want to extend our support and hope that everyone at the show tonight is safe. Right now our focus is on making sure everyone in the venue tonight is ok and gets home,” the band said.

A flyer for the event shows other bands set to perform on Friday evening were Revocation, Skeletal Remains, and Crypta.

An investigation into the collapse has been launched. Schadle said no first responders were injured, and so far everyone has been accounted for.