A fan shot a video and posted it on YouTube.
Initially, there were reports Chicago police pulled the plug on the show because the band was singing past the city's curfew. However, Live Nation, the concert's promoter said that was not the case and that the concert had to end because the venue at Northerly Island requires that all shows be over by 11 p.m.
The Backstreet Boys started their concert late and had several songs left they wanted to perform. They took to their Facebook page to deliver a message to fans.
"We got shut down five minutes shy of the finish line," the message read. "So we're so frustrated, and we're gonna figure it out how to make this right."
The Backstreet Boys actually tried to play one more song, but their microphones were cut.
Police also have said it was the promoter who ended the show early, while the band insists it was the police who shut them down.