(Cover) - EN Showbiz - Sugarland are "praying" after a stage collapsed onto their fans and killed at least four before a show in Indianapolis.

The American country music duo, comprising of Jennifer Nettles and Kristian Bush, were set to perform in the capital of US state Indiana last night.

Strong winds caused the staging for the outdoor concert to crash to the ground, killing at least four fans and reportedly injuring 40.

The band had been due to perform as part of the Indiana State Fair, and wrote on Twitter how devastated they are.

"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 (sic)," wrote the band.

Indiana State Police spokesman David Bursten has explained how a "strong gust of wind upset the rigging above the stage at the Indiana State Fairgrounds and caused a collapse of the structure over the stage".

He added that injuries range from "very serious to cuts and scrapes".

One of the concert's attendees has expressed the moment the disaster struck to the BBC.

"It was the worst thing I have witnessed in my life," said the witness.

"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." (C) Cover Media