The 65-year-old musician reportedly collapsed during the band's first song. Videos taken by audience members show Perry sitting down next to some amps while struggling to play, then stumbling backstage.
A concertgoer tells ET, "[He] was only on stage a few minutes when he sat down in front of the drum set. A few moments later he slouched over, slowly walked backstage and collapsed. The local EMT and FDNY rushed backstage to administer first aid."
According to the concertgoer, one of the EMTs told Depp and Cooper about the situation, and the band carried on with the concert.
According to Twitter user AeroFANatic, Cooper addressed the situation during the show, telling the audience, "If you notice one of our brothers is not onstage with us, he was very sick before the show."
Police sources told New York’s PIX 11 that Perry was rushed to Coney Island Hospital.
Later in the evening, Cooper took to Twitter to share an update on Perry's condition, writing, "Thanks to everyone asking about our brother @JoePerry. He is stable right now, with family & is under the best care."