At least 14 children have been injured in a woman with kitchen knife attack in a kindergarten in western China, police said.

The attacker, a 39-year-old woman, was arrested following the mass assault in the city of Chongqing on Friday morning but not motive has been made public, officers said.

Police said the stabbings at the Xinshiji Kindergarten in the city’s outskirts took place at 9:30am as the children were returning to classes.

The local force said all the victims were receiving treatment in a hospital. But it used social media to deny reports that two children had died of their injuries, urging internet users not to pass on “rumours”.

A doctor at the city’s Banan People’s Hospital confirmed the children were there but declined to give any details or his name, referring questions to the local government.

No other information about the attacker was given, other than her surname, Liu. Footage posted on social media appeared to show injured children walking to ambulances from the school gate, with some being placed on gurneys.

China has suffered a number of school stabbing incidents in recent years, blamed largely on people bearing grudges or suffering mental health problems.

In June, a man used a kitchen knife to attack three boys and a mother near a school in Shanghai, killing two of the children. Police said that assailant was unemployed and carried out the attack “to take revenge on society”.

Chinese law restricts the sale and possession of firearms, and mass attacks are generally carried out with knives or homemade explosives.

Almost 20 children were killed in school attacks in 2010, prompting a response from top government officials and leading many schools to add gates and security guards.