An attacker injured 20 children with a hammer Tuesday inside a primary school in China's capital, officials said.
Three of the children have serious but non-life-threatening injuries, the Xicheng district government said on its social media account, adding that the attack took place at 11:17 a.m.
The suspect, a 49-year-old surnamed Jia, was apprehended at the scene, the statement said. A native of northern Heilongjiang province, Jia was employed through a labor service company to perform daily maintenance work at the school. His contract was set to expire this month and had not been renewed.
As an expression of his dissatisfaction, Xicheng district said, Jia wielded a hammer that he normally used for work to injure students during a class.
All the injured children were receiving hospital treatment.
The school, Beijing No. 1 Affiliated Elementary School of Xuanwu Normal School, was founded in 1908. According to the school's website, it has 2,537 students and 199 teaching personnel.
Many schools in China have increased security following violence against students and family members.
In 2010, nearly 20 children were killed in knife attacks outside school gates.