A mysterious parcel with pieces of detonator was received by the office of Director General Border Security Force in New Delhi on Friday setting alarm bells ringing in the security machinery in New Delhi. The parcel sent through a private courier company based in Sonepat,Haryana was received in the CGO complex office here at 12.30 in the afternoon and sent the staff into a tizzy. It carried a book having a cavity in which pieces of detonators were detected. However,no explosives were found in it,official sources said. Showing presence of mind,the staff immediately informed the Delhi Police which rushed its bomb squad to the spot along with sniffer dogs,they said. Director General Raman Srivastava is on tour to Meghalaya border on . The police have arrested the courier boy who delivered the parcel and the address of the courier company is being verified,they said. Meanwhile,Home Ministry has sought a detailed report of the incident from the border guarding force,official sources said.