A gig came to an abrupt halt after The View lead singer apparently threw a punch at the band's bassist.
Fans were left shocked when the disturbance broke out between Kyle Falconer and Kieren Webster at The Deaf Institute in Manchester.
The set ended with the musicians walking off stage after the clash was captured in footage shared on Twitter.
Fan Saffie Yates, who had waited six years to see the band, said she first thought it was some sort of stunt.
She said: "It was very scary to see someone you respect behave like this.
"The bass player normally plays a couple of songs and it was his birthday yesterday. He wanted to play a third song and the lead singer went for him.
"He punched the bassist. I didn't know if it was part of the act.
"The band left the stage and the fans were hanging around waiting to see what would happen.
https://www.bbc.co.uk/news/uk-englan...ester-65558954