The Army Bomb Disposal Unit and the Gardaí have sealed off two houses in Co Donegal today.
Two suspect devices, thought to be pipe bombs, were discovered in Downings and Kilmacrennan.
One of the houses belongs to a well-known Donegal businessman while the second belongs to a relative of his.
The vehicle at the centre of the Downings investigation, believed to be a recreational vehicle, belongs to a family holidaying in the area.
The family are visiting a local Donegal family who would be well-known in business circles.
The businessman at the centre of the incident received a call from gardaí overnight.
They said they had received intelligence that a device had been left at a caravan belonging to him.
However, following a search of the area, the businessman then discovered the device had been left beside his house.
It followed an anonymous call to the Samaritans in Derry who then contacted the PSNI.
Gardaí have not issued a statement about the incident.