A 44-year-old man has been arrested over the stabbing of a teenager celebrating his 18th birthday, his father and three other men at a house party.
A sixth man suffered serious head injuries when a fight broke out in the early hours of Sunday morning in Tallaght, west Dublin.
The alarm was raised at around 4.20am at an address in Deer Park Avenue.
Gardai said five men - three in their late teens, one in his 20s and one in his 40s - were taken by ambulance to Tallaght Hospital with suspected stab wounds.
The arrested man was detained under section 4 of the Criminal Justice Act at Tallaght Garda Station.