Khang Tieu, 91, died at Riverside Community Hospital on Friday, according to authorities.
The crash happened Thursday afternoon at Magnolia Avenue. The bus company, Sina International, said there were 23 passengers and the driver on board.
The California Highway Patrol said all passengers sustained injuries. Many of the passengers had to crawl out of the emergency hatch on top of the bus.
The driver, 35-year-old Jian Fei Duan of Baldwin Park, suffered minor injuries. The driver was traveling 65 mph when he lost control and hit the center median guardrail. The CHP said that is "unsafe speed for roadway conditions."
It was raining at the time of the crash, but it's unknown if the wet weather was a factor.
The bus was heading to Garden Grove from the Pala Casino Spa & Resort in San Diego County. The Department of Transportation's safety record shows a clean record with no prior crashes.
Around the same, another tour bus crashed on the southbound 15 Freeway near Fallbrook in San Diego County. A 64-year-old woman from Van Nuys was killed in that crash.