TEHRAN, Young Journalists Club (YJC) - The car drove onto the square in Mishui town, part of Hengyang city in Hunan province, in the early evening on Wednesday, the Hengyang government said in a statement.
The driver, surnamed Yang but whose sex the government did not provide, drove the car alone onto the square, then attacked people using a spade and a knife, the statement added.
Yang has a long criminal record with previous convictions for selling drugs, theft and attacking people, which caused him to harbor a desire for "revenge on society", the government said.
Yang has been detained, it said, without giving other details.
Video images carried on state media showed several bodies on the ground as bystanders tended to some of them.
The government originally said three people died, but raised the death toll in subsequent statements.
There was no indication that the incident was terror related.
In February, 18 people were injured when a minivan caught fire and mounted the pavement in a busy part of central Shanghai and plowed into pedestrians.
Investigations showed the fire was caused by a driver who was smoking a cigarette inside the vehicle while illegally transporting highly flammable substances.
The government is generally nervous about such incidents after a car plowed through pedestrians in the northern part of Beijing's Tiananmen Square in 2013, killing the three people in the car and two bystanders.
Beijing blamed that on separatists from China's restive far western region of Xinjiang.