At least 14 Backstreet Boys fans have been injured after a metal structure at an outdoor concert venue collapsed in a storm in the US state of Oklahoma.
Staff were evacuating fans when rain and winds of 70-80mph (113-128 kph) knocked over the concert entrance trusses, the venue said in a statement.
All of the people injured were taken to hospital. Two have since been released.
In a tweet, the US band cancelled the show, saying: "We never want to put our fans in harm's way."
The venue hosting the concert, WinStar World Casino and Resort, said in a statement that it had asked its patrons to seek shelter from the storm at about 1700 local time (2200 GMT) on Saturday after lightning was spotted within four miles of the site.
"However, about 150 patrons who were standing in line for the Backstreet Boys concert did not heed staff's warnings," it continued.
When the storm hit, it knocked over trusses and the entrance collapsed on top of them. The casualties were treated at the scene and transported to nearby hospitals.
One fan, who said she witnessed the incident unfold, tweeted video showing emergency vehicles at the scene:
Current scene at #WinStarWorldCasino. My stomach is in knots. A pavillion collapsed in front of us on people waiting in line at the @backstreetboys concert. #oknews #BSB #okwx pic.twitter.com/7Km54rfbg7— Sydney Stavinoha (@SydneyStavinoha) August 18, 2018
A local reporter also tweeted images from the site:
Friend at the Backstreet Boys concert at Winstar Casino says an awning fell on people. She estimates 10 ambulances responded, paramedics took people out on stretchers. pic.twitter.com/egU2jJJEHS— Allison Harris (@AllisonFox4News) August 18, 2018
After the incident, the Backstreet Boys said they would try to reschedule the concert.
We never want to put our fans in harm's way and with tonight’s weather and the injuries from earlier, we have decided to cancel the show and will attempt to reschedule. The most important thing is for everyone to get home safely and we will see you all very soon!— backstreetboys (@backstreetboys) August 19, 2018
The venue also said it would be postponed for a later date.
Band member Kevin Richardson earlier tweeted that the show had been sold out with 12,000 fans expected.
We have a sold out house tonight. 12,000 +. So amazing! If it is safe, our lights & sound work and the weather holds we are going to GO FOR IT! But safety #1. Stand by. ✌🏻❤️— Kevin Richardson (@kevinrichardson) August 19, 2018
Before a decision was made about the show, fellow band member Nick Carter said safety must come first.
Waiting and praying for our fans that were injured. If we can perform were ready to go. But safety is first. pic.twitter.com/0GlB9fbmoc— Nick Carter (@nickcarter) August 19, 2018