The incident in Hanzhong was the sixth attack in and around Chinese schools this year.
Al Jazeera's Melissa Chan, reporting from Beijing, said news of the attack had been taken off Chinese language media websites.
"It looks like the government is trying to contain information about this, perhaps to prevent a nationwide hysteria," she said.
She said there had been no attempts by authorities to explain the recent string of attacks, but that a lot of discussions were taking place among Chinese citizens over the internet.
"A lot of people online have been talking about the possibility that there is very little recourse in China if someone has a grievance," Chan said.
"Perhaps this has become a way for somebody with a grievance to attract attention to their particular issue.
"The rule of law is a big problem in China. Going to court does not necessarily help a person in need so you might have situations where someone is making a last desperate attempt."
Victor Gao, the director of the China National Association of International studies, a government-affiliated think-tank, said the authorities were cautious about the release of information after the latest attack.
He told Al Jazeera that in previous cases, there had been detailed media coverage of the victims involved as well as of the criminals.
"I think there is a concern about such very widespread media reports mainly because inadvertently, it serves as a platform to give expression to the views held by those criminals," he said.
|Attacks in China this year
"It may create a situation where other people may want to use this ... killing innocent people to demonstrate whatever grievances they may or may not have."
Two weeks ago a farmer injured five children with a hammer in the eastern province of Shandong before fatally setting himself on fire.
The day before, a jobless man injured 29 children and three adults with a knife used to slaughter pigs in an attack at a kindergarten in neighbouring Jiangsu province.
Police said the man carried out the attack out of anger over a "series of business and personal humiliations", according to Xinhua.
Authorities across China have begun to strengthen security at schools, increasing police patrols near school grounds, and boosting the monitoring of people known to be mentally ill.
Police in a western district of Beijing have distributed 200 pitchfork-like implements to schools, for use by campus security and teachers to keep any attackers at bay.