Britney Spears Britney Spears

Problems with Britney Spears' Circus tour almost kept the show from going on in Vancouver, where the singer walked off stage during a sold-out concert.

Three songs into her performance Wednesday night, Spears left the stage while the GM Place audience sat in darkness for more than half an hour, according to the Vancouver Sun. A female voice told the booing crowd that the show was stopped because smoke was making everyone on stage uncomfortable, including Spears.

When the smoke cleared, Spears returned to finish her set, saying only "What's up, Vancouver?" during her performance of "Everytime. Closing the show with "Womanizer," she urged the audience, "Vancouver, don't smoke weed" — a remark sure to inspire rampant speculation about the source of all that smoke.

Spears' publicist said after the show that "crew members above the stage became ill due to a ventilation issue," according to The Associated Press.  

Spears kicked off the Circus tour, which spans North America and England, in New Orleans on March 3. The singer's father and attorneys are looking to expand the lip-synch-fest, according to the AP.