The man is being held at Letterkenny Garda Station.
A man in his 20s has been arrested, following the death of a young Donegal mother aged in her late 20s.
It is understood that the woman who died was a mother of two young children, a boy and a girl.
Two children are now in the care of grandparents.
Gardai were called to a house in Killygordon, Co Donegal in the early hours of this morning.
The arrested man has been detained under Section 4 of the Criminal Justice Act 1984 in Letterkenny Garda Station.
''Very distressed''
Local Cllr Patrick Mc Gowan told Highland Radio that the local community in Donegal is "very distressed".
"In the early hours of this morning, people were awoken by gardai and ambulances arriving.
"People are very distressed and shocked in the area. It's a very quiet area, it would be very seldom that you would hear any rumpus. It's a small area between Ballybofey and Strabane."
