The singer Morrissey is in hospital after collapsing on stage with breathing difficulties.
The 50-year-old former Smiths frontman was performing at the Oasis Leisure Centre in Swindon when the gig was cut short after a rendition of This Charming Man.
A spokeswoman for Swindon's Great Western Hospital said his condition was "stable".
Onlookers described seeing Morrissey "straining" to perform the song and slumping to his knees on stage, before two band members rushed to his side and dragged him offstage.
Eyewitness Mark Taylor, 40, told the Sunday Telegraph: "The stage went dark and he was taken off the stage and then his band then all left the stage. There was a wait of about 25 minutes before one of the stage crew came on and said Morrissey had left the building, and that he was seriously ill. Everybody started booing, thinking 'here we go again'. He has a bit of a poor track record for cancelling his concerts."
Jillian Moody said the crowd did not realise initially how serious it was and expected the singer to return to the stage.
She told the BBC: "It was interesting because a lot of people around us had bought tickets for Morrissey concerts earlier in the year. He has cancelled numerous concerts so they just thought that, you know, he had gone off but would be returning.
"I didn't think he looked particularly well but then again, he's well known as a reclusive character so I sort of thought that was just the way he was when he was on stage. He kept putting his hand up to his mouth as if he felt sick or... perhaps he was trying to hide something, but he didn't look particularly comfortable."
A spokeswoman for the Great Western Ambulance Service said: "Just after 9pm we got a call to a 50-year-old man who was reported to be suffering from respiratory problems and was unconscious.
"We sent a paramedic in a doubled-crewed ambulance. When they arrived they found a conscious patient who was not feeling well at all. They made an initial assessment and took him to the Great Western Hospital for further assessment."