Keith Walker, 36,  a father of three, from Tir na Ri Road, Clondalkin died.
And another man was shot in the arm at Shelerin Road, Clonsilla at about 18:00 local time.
His injuries are not life-threatening. The men were members of a pigeon club who were meeting in the yard at the time.
Police believe Mr Walker was not the killer's target and was shot in a case of mistaken identity.
People living in the area suggested that the shooting  was reportedly carried out by a gunman dressed as a woman.
A 32-year-old man was arrested in County Meath on Saturday morning.
On Saturday evening, two more men, aged 36 and 38, were also arrested.
Police have also searched a number of homes in Dublin.
Police have arrested two more men in the Republic of Ireland over a  fatal shooting in Dublin on Friday.