Green Day frontman Billie Joe Armstrong explained on Sunday that his band was unaware an aerialist had died on their stage at a music festival shortly before they went on.

Following the death of Pedro Aunión Monroy at the Mad Cool Festival in Madrid, Spain, late Friday night, Armstrong, 45, wrote in a lengthy essay on the Green Day website, “We are so sad for Pedro and his family and we pray for them in this time of grief. I can’t imagine how much suffering the friends and family are going through. Many of you are wondering why we continued to play our show after the accident. Green Day did not hear about the accident until after our show was over. We didn’t even know there was an acrobat performance at all.”

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Noting how large the festival is, Armstrong said the band was warming up at a backstage compound a half-mile from the stage, where they were scheduled to perform at 11:25 p.m. But 15 minutes beforehand, he wrote, they were “told by local authorities to wait to go on stage because there was some sort of security issue,” which he called not uncommon at any large show. “We were NOT told why, which is also normal . . . [and] we had no clue there was any such accident.”

After eventually getting the go-ahead, “The band jumped into vans and drove to the main festival stage. . . . We were on stage at around midnight and played around two-and-a half-hours. Everything seemed normal. The crowd and fans had a good time.” After then being driven back to the compound, they learned about Aunión, who according to the Spanish newspaper El País had fallen from a cage suspended by a crane roughly 100 feet in the air.

“All of us were in disbelief,” Armstrong wrote. “I don’t know why the authorities chose not to tell us about the accident before our concert. . . . If we had known prior to our performance we most likely would not have played at all. We are not heartless people. The safety and well being at any of our concerts absolutely comes first. What happened to Pedro is unthinkable. Once again we are heartbroken for his friends and family.”

The festival directors said in a message on the official website that, “For security reasons, the festival decided to continue with its programming. We send our most sincere condolences to all his family.”