Twenty children were wounded in an attack at an elementary school in Beijing Tuesday with three suffering serious injuries, local authorities said.A male suspect was brought “under control” and the wounded students were admitted to hospital, the Xicheng district government said, without elaborating on how or why the man carried out the attack.

Violent attacks targeting schoolchildren are not uncommon in China, which has seen a slew of deadly incidents over the past few years.Last April, a 28-year-old man killed nine middle-school students as they were returning home in one of the country’s deadliest knife attacks in recent years.

The killer, who said he had been bullied when he attended the school in northern China’s Shaanxi province, was executed in September.Later in 2018, a knife-wielding woman injured 14 children at a kindergarten in Sichuan province.