BEIJING — At least seven people were killed on Sunday morning by a knife-wielding attacker in northeast China, according to state media. Seven other people were also injured in the attack in the city of Kaiyuan, in Liaoning province, state broadcaster CCTV reported. A single suspect surnamed Yang has been arrested and police are investigating the case, the Kaiyuan municipal public security bureau said in a statement. The police did not mention the motive of the attack, or details on the suspect or the casualties. CCTV reported that a police officer who helped subdue the suspect was among the injured. A video posted by the state-run Beijing News on Chinese social media showed two police officers — one of them wielding a broom — confronting the suspect and tackling him to the ground. Knife attacks in public are not uncommon in China. In June, 37 children and two adults were injured by a knife attacker at an elementary school in the southwestern Guangxi region. In October 2018, a woman wielding a kitchen knife slashed at least 14 children at a kindergarten in the central city of Chongqing. Nine students were killed at a middle school in Shaanxi province in April 2018 by a 28-year-old man who was later sentenced to death. In 2017, 11 students were injured after a man climbed over the wall of a kindergarten with a knife and began attacking them. But perhaps the worst spate of stabbings occurred in 2010, which included a period of three consecutive days in which attackers targeted schools. China"s Ministry of Education responded to those events by ordering schools to strengthen security and bar strangers from entering campuses. — Courtesy CNN