Emergency services were called to reports of someone feeling unwell at the north London venue at around 10pm on Friday 30 November, but were unable to save the man. It is currently unclear what the cause of his death was.
Alexandra Palace issued a statement offering its condolences to the concertgoers family: "A medical incident occurred at last night's Bring Me the Horizon concert," it said.
"Our thoughts and condolences are with the individual's family and we would like to express our deepest sympathy to them. We hope you appreciate we cannot provide any further comment at this time."
Following the news, some fans who attended the show began to accuse the venue of having lax security measures, with one claiming he'd seen "more security at McDonald's".
Alexandra Palace then added to its statement on Sunday 2 December, writing: "We would like to clarify that this was a tragic medical incident and unrelated to the extensive security measures in place. However, we feel we must address inaccurate information. There were over 150 security personnel on site for the concert.
"Alexandra Palace has an experienced events team with security and full medical team stationed throughout the site. We work closely with our local authority, licensing and the emergency services to ensure that regulations and requirements relating to the planning of an event are always executed to a high standard."
Bring Me the Horizon said they were "horrified" to hear the news of "the death of a young man at our concert [last night]".
"Our hearts and deepest condolences go out to his family and loved ones at this terrible time," they said. "We will comment further in due course."
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