Upper Merion Township Police are investigating a smash-and-grab robbery at a high-end jewelry store in the King of Prussia Plaza.

It happened Wednesday afternoon at Tourneau, a store that specializes in expensive watches.

Police say three men with their faces covered used a small sledgehammer to smash a glass display case, grabbed a bag full of watches and headed for the parking garage.  They were in and out in about 20 seconds.  It’s the third robbery at the same store in less than two years.