The Contra Costa Coroner's Office identified him as 27-year-old Curtis Denton Jr. from Antioch, better known as prominent Bay Area rapper Young Kurt, according to The Mercury News.
Around 2 a.m., officers responded to Byron Highway just north of Holey Road and found Denton lying on the dirt shoulder outside of a 2019 Dodge Charger.
He was taken by ambulance to a hospital in Antioch, but died of his injuries there, CHP said.
Investigators determined that Denton was speeding southbound on Byron Highway and didn't navigate a turn in the roadway, striking the dirt shoulder and rolling the vehicle over several times.
He apparently was not wearing a seat belt and was ejected through the sunroof.
Fans and celebrities took to Twitter to express their remorse of Denton's death. Many described him as a Bay Area legend, who pioneered the rap scene from the Bay Area to Los Angeles.
Authorities have not yet determined if impairment was a factor, and are still investigating.
Anyone with information about the crash is asked to call the CHP's Contra Costa-area office at (925) 646-4980