They posed as dummies at a Beales store in Worthing, Sussex, alongside the real models on display.
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As soon as staff had shut up shop, they browsed the stock at their leisure picking out what they wanted.
Sussex Police were baffled as to how the gang - who are still on the run - got in without setting off alarms at the upmarket store.
This comes as one of the workers likened the raid to a heist seen in film Home Alone 2: Lost in New York.
They also called the incident a "very well-orchestrated crime" as police appeal for any information.
The alarm only sounded when they left the building via a fire escape with thousands of pounds worth of gear.
An assistant said the heist was a copy of the film, in which bad guys Harry and Marv plot to rob a toy store by hiding amongst the mannequins as it is locked up at night.
Beales is fitted with a sophisticated alarm system of sensors that should detect movement, and would have 'spotted' the burglars had they tried to break in.
The assistant, who asked not to be named, said: "It was only triggered when they left the store - it was a very well-orchestrated crime.
"They must have secreted themselves and pretended to be mannequins.
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"They probably dressed in clothes identical to those worn by the mannequins and stood there, not moving a muscle till the shop shut and everyone went home.
"They took oilskin jackets, high-end designer clothes and the like.
"It showed incredible nerve - the store is equipped from top to bottom with sensor alarms and cameras.
"They must have stood there with the mannequins not daring to move a muscle - imagine if they wanted to sneeze or had an itch they couldn't scratch!"
A spokeswoman for Sussex Police said: "We are investigating after the break-in was reported at Beales store in South Street.
"Clothing was stolen and the burglars left the store through the fire escape which set off the alarm. It is not clear how they got in.
"Officers are continuing to investigate. Anyone who saw anything or has any information is asked to contact police on 101 or on Crimestoppers anonymously."
A Beales spokesman said: "We do not wish to comment at this time."
In Home Alone 2: Lost in New York, Harry Lime and Marv Merchants, played by Joe Pesci and Daniel Stern, hide out in Duncans Toy Store on Christmas Eve.
But the hero Kevin McCallister, played by Macaulay Culkin, turns up and takes a picture before throwing a brick through the window to ruin their plot.