Riders were then sent crashing to the floor with shocked bystanders screaming in panic.
One witness reported the ride was about four or five metres in the air at the time of the accident.
He said: "Fortunately, it was not completely into its cycle, because if it was it would've been much higher up and more people would have been hurt."
One seriously injured victim was taken to the First People's Hospital in Tianshui City.
The remaining eight were taken to the Xingkang Hospital Observation to be checked over.
The ride has now been demolished and police are investigating.
Just last month a Chinese teenager died after being thrown out of a malfunctioned swing ride mid-air at an amusement park.
The accident occurred at Fengdu County in south-west China's Chongqing city, according to local media.
The girl, 14, was pronounced dead at the hospital after failed resuscitation attempts, reports said.