The area around Claudy RUC station in Co Derry will be sealed off overnight following the discovery of a suspect device at the back of the station.
The discovery was made late this afternoon and is being attended to by the British army bomb disposal squad.
Houses in a number of streets around the station have been evacuated and arrangements are being made to open a local hall for accommodation.
The RUC said in a statement that it is too dark to continue examination of the device and that the investigation will resume at first light tomorrow morning.
They appologised to residents who will not be allowed to return to their homes tonight: "Our duty is to protect the community therefore a very detailed, careful examination of the device is required.