Chinese police said this morning that an explosion that killed eight people outside a kindergarten yesterday was caused by a makeshift bomb and the bomber died in the blast.

The public security ministry said in a statement that the suspect was a 22-year-old man with health problems.

The suspected attacker, named only as Xu, rented a room near the kindergarten in the eastern town of Fengxian, where the blast occurred.

He had written the words "die" and "destroy" among others on a wall in his room where police found materials used to make a homemade explosive device, the statement said.

Xu made the bomb himself.

He had dropped out of school but was employed, the statement said without providing further details.