Twelve school children were injured during an anti-terrorist exercise conducted by Serbian police in the central Serbian town of Jagodina, reported Radio Television Serbia (RTS) on Monday. The children, seven of whom had been hospitalized, were hurt when a police helicopter descending on the field at the local football stadium blew over a number of banners lining the field. The plastic banners on wood frames were subsequently driven into the stands by the force of the helicopters rotors. Dr. Vesna Jarkin, a hospital director, said most of the injuries were minor, though one child suffered a broken collar bone and another received a concussion. The seven detained children have been kept overnight for observation, he added.