A 17 year old youth was charged at Buncrana Garda Station last night and was released on bail to appear at Buncrana District Court on the 8th of September.
A second man is still being questioned in custody in Buncrana, and is still being questioned.
Of the two men being detained at Letterkenny Garda Station, one man has been released pending a file to the Director of Public Prosecutions.
The second remains in custody.
The four were among five men aged between 17 and 24 arrested since Wednesday.
Another man was released without charge on Wednesday night.