Eleven young children died on Monday when the overloaded van they were travelling in plunged into a pond in east China's Jiangxi province, state press and a rights group said.
The accident happened as the van was taking the children to school and all of the 11 victims were between four and six years old, the Henan Business Daily reported.
It said that four other children, a teacher and the driver survived the crash, which happened in the morning near the city of Guixi.
Xinhua news agency, which initially reported only three fatalities, later said eight of the victims had died after they were transported to hospital.
According to the Hong Kong-based Information Centre for Human Rights and Democracy, emergency response teams took 70 minutes to arrive at the scene after locals informed authorities of accident.
The rights group said that the mini-van was overloaded and that its maximum capacity was just seven people.
China's roads are highly dangerous, with traffic laws and safety widely flouted, and truck drivers typically overworked.
Fatal accidents involving overloaded vehicles are also routine.
Last year, more than 62,000 people died in traffic accidents, state media said, citing police figures.
In August, 36 people died when a double-decker sleeper bus slammed into the rear of a methanol tanker and burst into flames in China's worst traffic accident in more than a year.
Both vehicles caught fire and only three of the 39 people onboard the bus survived the motorway crash, which occurred in north China's Shaanxi province.