Gardaí have confirmed that they are investigating an assault on four men at Mountcharles Co Donegal at about 5.50 am on Wednesday past.
Inland fishery officers in Co Donegal were held at gunpoint after confronting masked men using illegal nets to catch salmon.
The officers were surveilling the area when two men, wearing balaclavas and paramilitary style clothing arrived.
The officers were in hiding, the men then tried to flee when they made themselves known.
A rock was thrown at one of the officers which struck him on the head, resulting in six stitches being needed.
One of the masked men produced a hand gun after being cornered, threatening the officers to hand over their radios and surveillance footage.
The men then made their getaway on foot after forcing the officers to hand over their radio sets and surveillance equipment.