(CNN) -- A tour bus careened across a highway barrier and slammed into an oncoming box truck in eastern China on Sunday, killing 13 people and injuring 21 others, according to state media.
The bus had left Shanghai at 8 a.m. Sunday, heading toward a peony show about 100 kilometers (60 miles) away in Changshu, said the Xinhua report.
Around 9:25 a.m. in Changshu, the vehicle burst through the median on the Yanjiang Expressway and hit a truck heading in the opposite direction, the report said, citing the Jiangsu provincial government.
Both the bus and truck flipped over after the crash, as images from the scene showed.
The driver and six passengers on the bus were killed instantly, while six others later succumbed to their injuries, Xinhua reported.
Four of the 21 people injured were in critical condition at a nearby hospital.
Authorities are still investigating what caused the collision.