(Photo courtesy Chris Mitchell) Kriss Kross' Chris Kelly and Chris Smith reunited in February for a 20th anniversary concert for So So Def Records.
(CNN) -- Chris Kelly, one-half of the 1990s rap duo Kris Kross, died Wednesday at an Atlanta hospital after he was found unresponsive at his home. He was 34.
How Kelly died isn't known, and the Fulton County Medical Examiner's Office said an autopsy is planned for Thursday.
Kelly, together with Chris Smith, shot to stardom in 1992 with "Jump," which spent eight weeks on the Billboard Hot 100.
Going by the stage name Mac Daddy (with Smith known as Daddy Mac), the pair was known for wearing their clothes backward during performances.
Rapper Da Brat was shocked by Kelly's death. She had performed at a 20th anniversary party for producer Jermaine Dupri's So So Def label in February where Kris Kross reunited for one night.
"REST IN PEACE TO MY LIL BRO CHRIS KELLY OF KRIS KROSS. Dam wasn't we JUST at rehearsal and doin a So So Def20 show?," she wrote.
Michael Skolnik, editor in chief of the hip hop site Global Grind said: "i'm wearing my clothes to work backwards tomorrow."
Kelly and Smith were 13-year-olds when they were discovered in 1991 at an Atlanta mall by Jermaine Dupri.
The duo followed up their smash "Jump" with the single "Warm It Up." Together, the songs pushed their debut album, "Totally Krossed Out," to multiplatinum status.
Next came 1993's "Da Bomb." But the album failed to find the following of the duo's debut, in large part because the boys had hit puberty and they were marketed with a tougher image.
Their career never again reached the heights of their debut, but they continued to make music.
In 1996, the duo released the album "Young, Rich and Dangerous."
CNN's Chelsea Carter and Tresha Lindo contributed to this report.