An acrobat fell to his death in front of thousands of people at a music festival in Madrid Friday.

The performer, identified as Pedro Aunion Monroy, was a choreographer and experienced dancer. 

Organizers of the Mad Cool festival said in a statement Saturday that they regret “the terrible accident.”

“We send our most sincere condolences to all his family,” the statement said.

Video on social media taken from the crowd showed what appeared to be the acrobat plunging from a box suspended several metres in the air but it remains unclear what went wrong. The clip has been shared numerous times but CBC News has not been able to confirm who shot it.

Warning: some may find video below disturbing

Punk rock band Green Day took the stage as scheduled after the accident, which angered some fans who found it disrespectful.

Green Day posted on Twitter afterwards: “We just got off stage at Mad Cool Festival to disturbing news. A very brave artist named Pedro lost his life tonight in a tragic accident.”

The festival defended its decision, saying security officials advised them to move ahead with Green Day’s performance. In circumstances involving large groups of people, they argued, it could have been more dangerous to have “an uncontrolled movement of people” and “possible reactive behaviour” in a crowd of 45,000.

“Situations of panic and tension that would have been counterproductive and risky could occur,” a second statement said.

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Green Day, seen here performing in Cleveland in 2015, took the stage as scheduled, saying on Twitter they were only told of the death after their set. (Mark Duncan/Associated Press)

Mad Cool organizers say they’ll continue the festival over the weekend but will “render a heartfelt tribute to the artist” on Saturday. Kings of Leon, Wilco, M.I.A. and Foster The People are among the artists scheduled to perform.

“Pedro Aunion was a person committed to art that deserves all the respect and admiration.”

The dancer’s last Facebook post was made just hours before his death. He shared a photo of himself “flying” at the Mad Cool festival with the caption: “Tonight will be even more amazing.”