Gardaí in Donegal investigating fires in the Buncrana area in recent weeks have arrested two more people this evening.
The men, aged 20 and 21 are being detained at Buncrana Garda Station under section 4 of the Criminal Justice Act.
Of the original five men arrested, two have been charged while three were released without charge.
The arrests were made in relation to 11 incidents of fires in the Buncrana area since early July.
The attacks have been random and some have occurred in isolated rural areas.
Properties targeted include unoccupied buildings, farm sheds, vehicles and a health centre.