The incident happened in the city of Wenzhou in Pingyang county, the county's official Weibo account said.
A number of people fell from the ride and others were flung, said Xinhua state news agency citing witnesses.
Reports said the machine started moving before passengers had properly buckled themselves into it.
Pictures posted by news outlets on social media showed blood and people lying on the floor. They also showed the ride which has two passenger capsules that spin in a circular motion.
The capsules appeared to be more than three stories high at their highest point.
Two people are dead and four injured after an accident at an amusement park in south-eastern Zhejiang province in China, say local officials.