A controlled detonation at an explosives factory in the prefecture of Kilkis, northern Greece, almost went disastrously wrong on Saturday when a blast injured a local police chief and three other people and damaged more than 30 shops and homes in the area. Three employees of the company that owns the factory in Mandres were responsible for destroying explosives which had passed their use-by date. The head of the police station in nearby Nea Santa was overseeing the operation. Authorities said the controlled explosions were taking place in a specially constructed area at the factory. It is not clear what went wrong but a blast at about 2 p.m. resulted in the windows of 32 houses and businesses in Nea Santa and Mandres being blown out. Two of the employees were admitted to a hospital suffering from light injuries. The other worker and the police chief did not require hospitalization. A local prosecutor is looking into the matter.