Mr Burne said the window of opportunity had been brief but enough for them to gather up some items and get them out to the waiting car, as well as stack more property by the door ready for a quick removal.
He said the three were recognised from the camera footage and later arrested.
In two other recent incidents, people had been confronted after being spotted acting suspiciously on camera.
Both were seen trying to remove items from shops and were warned and trespassed.
In a third incident, a woman was seen by a staff member trying to make off with a laptop table and case.
She too was challenged and the property recovered - and was also warned and trespassed.
"Some retailers just want their product back but not the thief, hence the warning and trespass notices being issued in some of the incidents," Mr Burne said.
He said one thing they had shown up was the danger of leaving stock in areas which were not in sight of staff or cameras.
"Like outside the entrance."
Thirteen pairs of slippers were stolen from a display out the front of a Pandora business recently.
Staff attendance was also crucial, he said. "It's always good to have some form of warning device so if you leave the shop floor for a few minutes when no one is there you'll know when someone does come in.
"Thieves love it when they walk in and there's no assistant in sight and love it even more when there's nothing to alert anyone to their presence."