Chinese authorities say a homemade bomb was used in an explosion at the front gate of a kindergarten that killed eight people, including the suspect.
Police say the 22-year-old male suspect was identified primarily using security camera footage and DNA collected at the blast scene. They provided only his surname, Xu, but no motive.
Investigators say they found materials for making a homemade bomb at Xu's nearby residence. They say emblazoned on the walls of the residence were the Chinese characters for death and disaster.
The police announcement says Xu had left school because of an autonomic nervous system disorder, whose symptoms can include dizziness and problems with basic bodily functions.
Eight people were killed and 65 injured on Thursday in an explosion at a kindergarten in eastern China that police have described as a "criminal" act, state media said.
The blast took place around 5 pm near the entrance of the kindergarten in Xuzhou, in the coastal province of Jiangsu, Xinhua said.
Two people died on the spot and six more died of their injuries in hospital. Xinhua reported that the number of injured had risen to 65 by 11 pm on Thursday, with eight in critical condition.
Local authorities held an early-morning press conference on Friday and said that contrary to early reports the blast did not occur while parents were picking up children after school.
According to the People's Daily, no kindergarten students or teachers were injured in the blast.
Pictures circulating on Chinese social media showed about a dozen women and children lying on the ground in what appeared to be the immediate aftermath of the blast.
Blasts and other accidents are common in China, because of patchy enforcement of safety rules, although the government has pledged to improve checks to stamp out such incidents.
Police from Xuzhou city urged social media commentators to share only information from official channels after some users posted videos of an April explosion which they said depicted Thursday's incident.