Larry Harvey, co-founder of the annual art festival Burning Man, died Saturday morning in San Francisco. He was 70 years old.

Though the cause of death has not been confirmed, Marian Goodell, CEO of the Burning Man Project, revealed Harvey had suffered a massive stroke on April 4.

“We resolutely held out for a miracle. If there was anyone tenacious, strong-willed, and stubborn enough to come back from this challenge, it was Larry,” Goodell wrote on the festival's website. “Though we all hoped he would recover, he passed peacefully this morning at 8:24 a.m. in San Francisco, with members of his family at his side.”

Harvey and his good friend Jerry James hosted the first Burning Man in 1986 on Baker Beach in San Francisco. The inaugural event, which was reportedly attended by 12 people, was billed as a summer solstice ritual that involved burning an effigy of a man. The festival has since evolved into a major week-long event in Nevada's Black Rock Desert, attracting up to 70,000 people per year. Notable attendees include Diddy, Will Smith, and Diplo.

“Burning Man culture has lost a great leader and an inspiring mind. He adeptly interpreted the manifestation of what became a movement. I have lost a dear friend who I’ve known, loved, and worked beside for nearly 22 years,” Goodell wrote. “The loss of his presence in our daily lives will be felt for years, but because of the spirit of who he is, we will never truly be without him. Larry would be the first to say this isn’t an ending but the start of a new chapter, and we all have a hand in where we go from here.”

This year's festival will take place from August 26 through September 3.