Fifth Harmony temporarily became a foursome on Friday night (September 2) when member Camila Cabello abruptly left the stage during the group's concert in St. Louis, Missouri.

The singer's departure reportedly took place immediately after the 2016 MTV Video Music Award winners performed their 2015 single, "Bo$$."

According to the St. Louis Post-Dispatch, the group told concertgoers that Cabello, who did not return to the stage, left due to a wardrobe malfunction. However, the artist later revealed on Snapchat that she was forced to walk offstage after suffering an anxiety attack.

"Hi Missouri, sorry I couldn't finish the set last night," she wrote. "Was having too much anxiety and couldn't finish it...I love you. I'm truly sorry."

Cabello further hinted she may also be suffering from exhaustion, tweeting on September 2, "[I] just wanna sleep for 3 days."

Across Twitter, Harmonizers have been sending words of support for the "I Know What You Did Last Summer" singer along with the hashtag #WeAreWithYouCamila. Read some of their messages, below:

Cabello isn't the first artist to struggle with anxiety onstage. In June, Zayn Malik was forced to cancel his performance at CapitalFM's Summertime Ball in London.

On Instagram, the "Pillowtalk" singer cited severe anxiety as the cause of his cancellation, writing, "Unfortunately, my anxiety that has haunted me throughout the last few months around live performances has gotten the better of me."

Fifth Harmony Are Chic in Classic Black on 2016 MTV VMAs Red Carpet: