Gardaí and the Coast Guard will resume a search of the Sliabh Liag area of Co Donegal on Tuesday following reports that a person has gone missing.
The area, where Europe's highest sea cliffs are located, was cordoned off on Monday as a result of the search.
The identity of the missing person has not been released.
The Coast Guard, Gardaí and the Rescue 118 helicopter from Sligo are involved in the search, as are members of the Donegal Mountain Rescue Team.
Gardaí have restricted access to the area as the search continues.
In what is believed to be a connected incident, gardaí have also sealed off a house in the Killybegs area.
Forensic officers entered the property and a search has being conducted.
Uniformed officers remain at the house, however, gardaí have not released information regarding the nature of the search.
A spokesperson said they have no further details in relation to the investigation, but added that updates will be provided when they become available.
