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 40 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 21:00 local time (01:00 GMT), said the paper.

Video footage posting 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.