A knife-wielding man carried out knife attack outside the gate of a primary school in Shanghai on Thursday, killing two pupils, injuring one adult and one pupil, local police said in a statement.

The incident took place at around 11:23 a.m. local time. The attacker, identified as a 29-year-old jobless man surnamed Huang, has been detained. 

Police said a further investigation is underway.

In April, nine people were killed by a knife-wielding man near the No.3 Middle School in Mizhi County, northwest China's Shaanxi Province.