Violence broke out at a Dropkick Murphys concert in Chicago, Ill., leaving two fans in stable condition with knife wounds.

The attack apparently happened at the gates of the Huntington Bank Pavilion at Northerly Island, where the Dropkick Murphys were appearing on Tuesday night (Aug. 8) with Rancid. An argument broke out among three people just before 9:30 p.m., as security personnel were using wands to check for weapons.

The Chicago Tribune reports that the brawl apparently spilled into the concert space. When it was over the as-yet-unidentified attacker had stabbed a 29-year-old man in the neck and face, and cut a 34-year-old woman in the abdomen area.

A witness said the male victim "was bleeding pretty bad," while another told ABC7 that "it's disappointing there's a stabbing here at this good concert."

Both victims were taken to Northwestern Memorial Hospital, while the attacker was arrested. A weapon was recovered at the scene, according to NBC Chicago, and charges are pending. No other injuries were reported.

Chicago Park District General Counsel Tim King is now aiming tough questions at the firm hired to handle security at the venue for the Dropkick Murphys show.

"We're working with LiveNation and police to try to get to the bottom of it. We have to find out what the heck happened," King told ABC7. "Did somebody sneak in a knife in their shoe or throw a knife over the fence? We're still piecing it together. And if we need to improve security, we will to make certain it's a completely safe environment."

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