The sniper who has killed nine people in the area around the US capital Washington has issued a warning that children are under specific threat, according to police. The warning comes as officers made a fresh appeal for the sniper to contact them over demands made in a message left at the scene of the last confirmed shooting, on Saturday night. It is rumoured that the note contained a demand for a large sum of money. Montgomery County Police Chief Charles Moose read out part of a message the police believe was from the sniper. It read: "Your children are not safe anywhere or at anytime." Mr Moose urged the sniper to make contact with law enforcement officials about "options".