Police in the Republic are investigating a video shoot by suspected dissident terrorists in a remote forest.
Two trained rescue volunteers stumbled upon the gang while searching for a missing dog. The gang of four men and two women were all dressed in paramilitary uniforms and had tripods, camera gear and lighting equipment.
Peter Brown, from the Donegal Mountain Rescue Team, was out training his search dog Buddy when the incident happened.
"It was a suspicious set of circumstances," Mr Brown said.
"I had a colleague with me and Buddy went missing. He's trained to track down people and he just disappeared into the forest. One man suddenly appeared and threatened my colleague to stay out of the forest."
The incident happened in the Muff area of Co Donegal late on the night of Saturday, March 2.
"I have no idea what those people were up to and I can't say for certain what they were doing, but they were dressed in camouflage gear and had filming equipment," Mr Brown said.
The dog was found unharmed. several hours later.
A Garda spokesman said officers are investigating the incident. One officer said the fact the rescue workers were threatened made it "all the more alarming".