Comedian Ian Cognito died of a heart attack during his performance at The Atic bar in Bicester, England, Thursday, according to the BBC.

When the 60-year-old comic took a seat on stage and began breathing heavily before falling silent for five minutes, the crowd initially thought it was a joke, Compere Andrew Bird, the owner of the venue’s Lonely Wolf Comedy Club, told the BBC.

Fans continued laughing, believing nothing was wrong — until South Central Ambulance Service later confirmed that Cognito had died at the scene, the BBC reported.

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According to Bird, Cognito had been feeling sick before the show started but insisted on performing anyway. He even joked during his set, “Imagine if I died in front of you lot here,” Bird said.

“He was like his old self, his voice was loud. I was thinking ‘he’s having such a good gig,'” continued Bird, who was the first to check on Cognito on stage. “Even when I walked on stage and touched his arm I was expecting him to say ‘boo.'”

When the crowd realized Cognito wasn’t playing a practical joke, a pair of off-duty nurses and a police officer performed chest compressions and called an ambulance.

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Audience member John Ostojak told the BBC: “We came out feeling really sick, we just sat there for five minutes watching him, laughing at him.” Ostojak recalled hearing Bird say that dying on stage is how Cognito “would have wanted to go… except he’d want more money and a bigger venue.'”

Cognito was born Paul Barbieri in London in 1958. He had been performing comedy since the mid-1980s.

Several comedians have taken to Twitter to react to Cognito’s death, including stand-up comedian Jimmy Carr.

“Died with his boots on. That’s commitment to comedy,” he said. “I’ll never forget his kindness when I started out & how god damn funny he was.'”

Veteran stand-up comedian Ian Cognito has died on-stage – literally. The audience thought it was part of the act. Died with his boots on. That’s commitment to comedy. I’ll never forget his kindness when I started out & how god damn funny he was. — Jimmy Carr (@jimmycarr) April 12, 2019

Comedian Shappi Khorsandi also tweeted, “Such a sad shock… one of the people who made this job brilliant from the very beginning has gone.”