A woman has stabbed at least 14 children at a KINDERGARTEN in Chongqing in central China with a kitchen knife, local police said Friday.

Chongqing City Banan District police said the children were slashed as they walked back to class after their morning exercises at Yudong New Century Kindergarten about 9.30 a.m. local time.

School security guards and staff managed to restrain the 39-year-old attacker. Video from the scene appeared to show angry onlookers hitting and kicking the woman after she was detained.

An unknown number of students were taken to hospital following the incident, according to the statement, while the female attacker was taken into custody.

Chongqing resident Xia Yang told CNN large crowds gathered at the scene following the incident, and videos of injured children are circulating on Chinese social media. Police said investigations are continuing.

Friday’s incident isn’t the first time children in China have been hurt at school by people wielding knives. Nine students were killed at a middle school in Shaanxi province in April by a 28-year-old man who was later sentenced to death.

According to state media Xinhua, the killer had wanted to “get revenge on his former classmates who had teased him” and had bought the knives online.

In 2017, 11 students were injured after a man climbed over the wall of a kindergarten with a knife and began attacking them.