The suspect has been identified as 22-year-old Xue.
"This person had psychological problems. After he left the university, he rented a house in the city and working at the school where the bomb blast has taken place", state run Chinese television quoted investigators as saying.
The police found bomb-making facility in his house. He had written the words "die", "death" and "destroy" on the walls of his house.
Chinese police routinely blame people with psychological problems for such attacks without providing details.
Also Read
Sixty-six people were injured in blast that rocked the school yesterday. There were no children or teachers among the casualties, state-run Xinhua news agency reported.
The condition of the eight of the injured was stated to be serious.
The blast occurred around 4:48 pm at the gate of the kindergarten. Two persons died at the scene, and another six died later in hospital. The condition of the eight of the injured remained critical, doctors said.
A team led by Huang Ming, deputy minister of public security, has been sent to investigate the blast.
A witness told the Hong Kong-based South China Morning Post the blast came just minutes before the end-of-day bell rang.
"At about 5pm, we heard a blast and thought it might have been a gas explosion at a nearby food vendor," a local shop owner was quoted as saying by online news portal Sohu. "Many people might be dead".
A shop-owner near the kindergarten, who declined to be identified, told the Post the blast happened a few minutes before the kindergarten opened its doors to allow parents inside to collect their children.
"Because the explosion happened just outside the school grounds, the students waiting inside classrooms would probably have been shielded from injury," he said.
His daughter attended the school and was later taken home safely by her grandfather, he said.
Disclaimer: No Business Standard Journalist was involved in creation of this content