The Mizhi county government said on Weibo that two students had died of their wounds in hospital. It said initially that seven children were killed and 12 injured.
The 28-year-old man, a former student, attacked schoolchildren on their way home. The suspect was promptly detained. He confessed he wanted to get revenge for having been bullied.
Stabbings, including at schools, are not uncommon in China. Last February, a man stabbed a woman to death and injured 12 other people at a shopping mall in Beijing.