A woman in her late 60's died after she was shot at a house in Killinarden in Tallaght at around 4 o'clock yesterday afternoon.
Her body remained at the scene over night.
Meanwhile, a second woman, in her mid 30's also sustained gunshot injuries and is being treated in hospital. Her injuries are described as non life threatening.
Gardai are questioning a man in his 50's who was arrested a short time later.
Elsewhere, in a separate incident, Gardai are appealing for witnesses after a man in his 40's was shot at a house on Earlsfort View in Lucan at 7 o'clock last night.
He was rushed to Tallaght hospital, where he was later pronounced dead.
Post mortem examinations have yet to be carried out.
