MONTREAL – Thousands of Lady Gaga fans were left disappointed Monday night when the pop star cancelled her performance at Montreal’s Bell Centre.

The singer tweeted at about 5 p.m. that she got sick while singing in the rain during her recent show at New York’s Citi Field.

Promoter Live Nation said on its website that Lady Gaga has been told by her doctor to reschedule due to respiratory infection and laryngitis.

“I sing this entire show live, and pride myself on giving it all, but when I sang in the rain at Citi Field I got sick and have been pushing through,” Lady Gaga said in a tweet.

“To my beautiful fans. I couldn’t be more devastated that I am unable to perform tonight. I am so sorry to anyone who had their heart set on seeing me tonight.”

Lady Gaga later tweeted that she was sending free pizza to any of her fans outside The William Gray hotel in Montreal with the message “I love u so much & I’m so sorry u are the most loyal fans.”

The promoter also said the tour is working on rescheduling the performance, so fans should hold onto their tickets pending additional information.

Lady Gaga is scheduled to perform in Toronto at the Air Canada Centre on Wednesday and Thursday before continuing her Joanne World Tour in the United States.

Marie-Anne Sirois, a 22-year-old fan who had waited eight hours to get into the Bell Centre, said “everyone was shocked” when Lady Gaga made her announcement on Twitter.

“It was madness, it was really chaotic, everyone was crying,” said Sirois in a telephone interview a few hours after the cancellation.