Six people have been arrested near Dungannon in Co Tyrone, in a follow-up investigation to a public order incident in Co Longford yesterday in which a man was stabbed.
The PSNI said an armed response unit stopped a vehicle travelling on the M1 towards Portadown following a request from gardaí.
Seven men and one juvenile were in the vehicle.
A large bladed weapon was found during a search and police said six males were arrested for possession of an offensive weapon, grevious bodily harm with intent and money laundering.
A number of people are believed to have been involved in a confrontation on Ballymahon's main street in the early hours of yesterday morning, during which a man in his 40s was stabbed.
It is believed the confrontation was between members of two related families who had travelled from the UK to Ireland for a memorial event in Longford town.
The injured man was taken to the Midland Regional Hospital, Mullingar, before later being transferred to St James's Hospital in Dublin, where he is said to be in a serious condition.