A mortar bomb blast inside a religious school in northern Afghanistan Thursday killed at least seven students, police said. "As per initial investigation, the explosion was caused by a mortar that had somehow been carried inside the madrassa," police spokesman Khalil Asir told AFP. The blast happened in Ishkamish district of Takhar province. Provincial governor spokesman Jawad Hejri confirmed the incident. str-us-jds/ecl/fox