Image caption Witnesses said the wind hit minutes after a safety warning was given on stage

At least five people have died after a stage collapsed at a concert in the US state of Indiana, officials say.

The authorities said the stage came down during a storm at the Indiana State Fair in Indianapolis as the band Sugarland were about to perform.

Police said another 45 people had been injured, some critically. A number of people were trapped under the wreckage.

The Indianapolis Star newspaper said winds of up to 60mph (96 km/h) had been felt at the site.

The collapse happened as some of the 12,000 concertgoers were being evacuated from the Hoosier Lottery Grandstand at around 2100 local time (0100 GMT), said the paper.

It almost seemed like a hurricane hit out of nowhere Chris, Concertgoer In pictures: Indiana stage collapse

Video footage posted online showed crowds screaming as strong winds brought the staging structure down in seconds.

The official State Fair Twitter feed asked people to wait for more information on the tragedy.

"Our prayers are with the families of all affected," it said.

Four people were initially confirmed dead but another died of injuries overnight, Indiana police said. The victims have not been identified.

Media reports said a number of children were among those taken to hospital.

Capt Brad Weaver of Indiana State Police said he had just given a safety announcement on stage when the winds hit.

He had taken cover behind a trailer and "saw the framework from the stage start to come over".

Pure pandemonium

Capt Weaver said security officials and members of the public immediately helped to lift the staging to free people trapped underneath.

He told a press conference he did not believe there was anything else that could have been done to prevent to collapse.

Media playback is unsupported on your device Media caption Video taken at the event shows the stage collapsing as people screamed

A man named Chris who attended the concert told the BBC: "It was the worst thing I have witnessed in my life."

"We could see the sky get really dark and there was lightning and thunder. It almost seemed like a hurricane hit out of nowhere.

"The stage just leaned to the right and crashed down. It felt to me like it was in slow motion. Everyone was scrambling and it was horrifying because you knew people were underneath it."

Stacia Matthews, a reporter for RTV6, said the scene was "pure pandemonium".

"All the aluminium, the light fixtures, speakers - all of that collapsed onto the stage and onto the track where children and adults were waiting for the concert to begin," she told the BBC.

"People said they dove underneath the debris to remove people who were trapped."

Some of those who died were believed to have been members of the crew who had been working on the light rigging, she said.

Indianapolis Star reporter David Lindquist said the staging "fell from left to right".

"This is bad, very bad", he told the paper. "You could clearly see people were under the footprint of the rigging."

But he said it took rescue workers less than 20 minutes to free those trapped.

Another witness, Aaron Richman, told CNN: "You could see a lot of people panicking. All the scaffolding and speakers - all that came crashing down - and the whole stand just collapsed."

Sugarland's singer Jennifer Nettles said the band were "stunned and heartbroken" by the incident.

"We hold those injured in our prayers at this very sad time. There are no words. It is tragic."