A man was reportedly carrying a gun at a polling station in Northern Ireland, police said.
Nobody was threatened at the venue and detectives are following a definite line of enquiry, it is understood.
Voters in West Tyrone have gone to the polls for a Westminster by-election caused by the resignation of former MP Barry McElduff.
A Police Service of Northern Ireland (PSNI) statement said: "Efforts are continuing to locate him and enquiries into the matter are ongoing."
Police in Omagh received a report of a man acting suspiciously at a polling station on the Crockanboy Road, Greencastle, just before 1pm on Thursday.
They said: "It was reported that the man may have been carrying a firearm."
Ulster Unionist West Tyrone Westminster candidate Chris Smyth said there was now a strong, armed police presence at the scene.