Seven teenagers are now being questioned in connection with the murder of 19-year-old David Byrne, who was stabbed to death in Dublin at the weekend.
The six boys and one girl have been detained on suspicion of murder and withholding information.
They are being held at a number of garda stations in the city.
Mr Byrne, from Davitt House in Drimnagh, died in the car park of the Emmet Court apartment block in Inchicore.
He was chased for around 400m before being stabbed at least four times.
Gardaí have appealed for witnesses to the incident to contact them in Kilmainham on 01-6667300.
David Byrne was not a major criminal and only had minor convictions for road traffic offences.
He had been attacked and stabbed before and had associated with members of one of the Crumlin-Drimnagh feuding drugs gangs.