(CNN) -- Sean Kingston is walking around Miami's Jackson Memorial Hospital eight days after he was brought there in critical condition following a personal-watercraft crash, the publicist for Epic Records said Monday.
Kingston, 21, has been upgraded to serious condition, publicist Joe Carozza said.
"Sean is breathing on his own and walked for the first time this morning," Carozza said.
Two sources close to the hip-hop artist told CNN last week that doctors expected Kingston to need about six weeks to recover.
He suffered a broken jaw, a fractured wrist and water in his lungs, according to the sources, who both asked not to be identified since they were not authorized to speak to the media.
Cassandra Sanchez, 23, was riding on the Sea Doo personal watercraft with Kingston when it crashed into a Miami bridge on May 29, according to an accident report from the Florida Fish and Wildlife Conservation Commission. Sanchez was also injured and hospitalized.
Kingston had bought the Sea Doo just days before, as he was moving into a new house in Miami, one of the sources said.
His life vest apparently fell off during the crash, causing him to sink below the water, according to witnesses.
"They were calling us over, telling us, 'He's drowning, he's drowning,' " said Carmen Rivera, who was boating nearby with her husband, Jonathan Rivera, and friend Jimmy Vega. The three rescuers were interviewed by CNN affiliate WSVN-TV.
"We jumped in the water to help him keep his head above water," Vega said.
"I pushed him up, and he was vomiting what seemed like water, and then there was some blood coming out," Jonathan Rivera said.
The Miami-born artist changed his name from Kisean Anderson to Kingston to reflect his Jamaican heritage.
He shot to fame in 2007 when his debut song "Beautiful Girls" became a No. 1 hit in the United States.
CNN's Denise Quan contributed to this report.