Six people were killed and another was injured in an attack at a kindergarten in Lianjiang city, Guangdong province, on Monday, according to local media.
A male suspect surnamed Wu was detained, the Lianjiang public security bureau said in a statement.
According to the bureau, the incident took place at about 7:40 am.
Wu, a 25-year-old native of Lianjiang, which is administrated by Zhanjiang on the Leizhou Peninsula, was taken into custody at about 8 am.
Police did not reveal details of the case, saying an investigation is underway.
According to an online video published by ThePaper.cn, the tragedy took place in a kindergarten, and onlookers found a child and two adults on the ground in front of the kindergarten.
Another online video published by Shanghai Media Group showed a man waving a knife in front of the school. The dead and injured include teachers, parents and children, said Shanghai Media Group.
Pushed-over electric scooters were visible at the scene, and blood was apparent on the ground, according to the video.
A young man was seen being subdued and taken away by police, the video showed.