As told by Billboard:
Ten minutes into a set that began at 1:30 p.m., Rae Sremmurd performed their song “Unlock The Swag” when Slim Jimmy tumbled off a speaker in front of the crowd. The rapper was carried back onstage with the help of two security guards and placed behind the DJ booth.
His Rae Sremmurd partner, Swae Lee, cut off “Unlock The Swag” after a few bars to examine the situation. He then told the crowd, “This shit is pretty crazy. … This n—a’s leg is like, split open, I’m serious.”
The duo’s DJ added into his microphone, “Go pray for Jimmy tonight. He’s hurt real bad.”
Minutes later, Jimmy was handed a microphone and spoke to the crowd from behind the DJ booth. “I got a big ass piece of glass in my leg, so if you got that video, put that shit on Instagram,” he said to audience cheers. He also asked Swae to continue the performance, which the rapper did by himself, with Rae Sremmurd tracks like “My X” and “No Type.”
UPDATE: More Instagram posts below, including a video of what occurred.