A school bus ploughed into a crowd of people outside a middle school in eastern China on Tuesday, killing 11 people including five students, state media reported.

State broadcaster CCTV said the driver "lost control" of the vehicle as it approached the school in Shandong province's Tai'an city at 7:27 am (2327 GMT Monday).

The bus ran into a group of parents and children on the side of the road, according to CCTV.

"As of now, (the incident) has caused the deaths of 11 people, of whom six were parents and five were students," the broadcaster reported in an update just after 11:30 am.

It said one other person was in a "critical" condition, while the vital signs of another 12 people were "stable."

Images circulating on social media showed adults kneeling over children in blood-soaked clothes lying in the road next to a hulking grey bus.

The images were initially unverified, but AFP was able to geolocate them to the school in Shandong where the crash took place.

The driver was being held by local police and the cause of the incident was "under investigation," CCTV said.

Many public schools in China reopened for the new academic year this week.

Deadly traffic accidents occur frequently in the country due to lax safety standards and widespread disorderly driving.

In July, police said a vehicle crashed into pedestrians in the central city of Changsha, killing eight people and injuring five.