Two people were stabbed at a Rancid and Dropkick Murphys show in Chicago.
The bands were playing at the Huntington Bank Pavilion on Northerly Island. Local police said that the man and woman affected were arguing with their attacker in a bar area that "spilled out into the venue."
The attacker then stabbed the man in the neck and face, while the woman suffered lacerations to her abdomen.
They were taken to Northwestern Memorial Hospital where their conditions were stabilised. Their alleged attacker was arrested, with charges pending, and a weapon was recovered at the scene.
"You know, I felt safe, but at the same time I could totally see how somebody slipped past security," commented a concert-goer.