Stand-up comedian Ian Cognito has died following a heart attack while performing on stage.

The comic had been doing a set at The Atic bar in Bicester on Thursday night when he sat down on a chair and "laid back for five minutes." Audience members reportedly thought this was part of Cognito's performance and continued to laugh along. He was later pronounced dead by the south central ambulance service. BBC News reports that the comic had been joking about having a stroke just 10 minutes before he passed away. Audience member John Ostojak, who was attending the gig with a friend, said he assumed Cognito's apparent illness was part of his act. "Only 10 minutes before he sat down he joked about having a stroke," Ostojak said. "He said, 'imagine having a stroke and waking up speaking Welsh.' When he came out feeling really sick, we just sat there for five minutes watching him, laughing at him." An ambulance was eventually called by a member of staff. They asked the audience to leave and performed chest compressions while waiting for emergency services to arrive. Cognito won the Time Out Award for stand-up comedy in 1999. Fellow comedians have taken to Twitter to share their shock and condolences following the comic's passing. "Such a sad shock," said Shappi Khorsandi on Twitter. "Ian Cognito has died." "One of the people who made this job brilliant from the very beginning has gone. I got so excited to be on bills with him and watch him work and have a beer after. And those eyes! Those beautiful eyes." Rufus Hound also remembered Cognito, saying: "We have lost one of the greats."