A Chinese villager is suspected of killing his parents and then 17 neighbours in an attempt to cover up his crime, police said.
An investigation in the south-western Yunnan province found that Yang Qingpei argued with his parents over money on Wednesday evening before killing them, according to reports.
Fearing he would be identified as the killer, it is alleged that he then murdered 17 of their neighbours.
There were no details on how Yang allegedly killed the villagers.
This marks one of the bloodiest mass slayings in China in recent years.
Because firearms are tightly controlled in China, mass killings are usually carried out with knives, poison or home-made explosives.