Ice T and Russell Simmons remember Kool DJ AJ on Twitter

Kool DJ AJ has died, according to rapper Kurtis Blow who wrote about the news on Twitter Wednesday. “Rip my friend Kool DJ AJ,” he captioned an Instagram photo of the late DJ, who began working in hip-hop in the ’70s, a few hours later. His cause of death is currently unknown.

Def Jam co-founder Russell Simmons and rappers including Ice-T, Chuck D, and Big Daddy Kane also paid tribute to DJ AJ on social media. “DJ AJ a great pioneer in the rap game has passed away [today],” Simmons tweeted. “Amazing sweet spirited human being.”See their posts below.