"Somebody get up there. Hey, hey, hey!" Robin Thicke added.
Comedian Ken Jeong, who is also a physician, jumped up to head to the stage and said: "She's choking! Get a medic right now."
Fortunately, medics responded and were on hand to help Firefly as they went to the podium to help her remove the mask.
One of the medics could be heard saying: "I'm right here to take off [your mask]" as the screen faded to black.
Sending our love to #FireflyMask. #TheMaskedSingerpic.twitter.com/3h5lGXkNYD
— The Masked Singer (@The Masked Singer)
According to Gold Derby, Nick Cannon, who hosts the show, told the audience the following, in part: "She's backstage right now being looked after by our set medic. Her wellbeing is our top priority. But for now, the show must go on".
He then introduced the next singer, Ram. When the performance was done, he gave another update on Firefly.
"The good news is, Firefly is one heck of a fighter," and added that she was back on the stage.
"Let's do it, let's do it," Firefly said as the audience cheered her on.
After the performance, McCarthy, Jeong and Thicke gave her a standing ovation, with Thick mentioning backstage that she gave the 'best performance" of the evening.
This premiere episode wasn't the only dramatic moment on The Masked Singer stage that night.