By Steve Beck

KING OF PRUSSIA, Pa. (CBS) – A $40,000 reward is being offered in connection to an armed smash-and-grab robbery at a high-end watch store in King of Prussia.

The robbery happened at about 8:10 p.m. on April 13th at the Tourneau, Inc. fine watch store located inside the King of Prussia Mall.

According to investigators, five masked men entered the store and restrained the store’s security guard at gunpoint while they smashed the glass display cases with sledge hammers and removed numerous watches.

The robbery lasted less than a minute and the suspects quickly ran out of the store. The amount of merchandise stolen has not yet been determined.

The five suspects were described by witnesses as black males wearing masks.

The security guard suffered a minor injury from being struck by one of the robbers. There were no other injuries reported.

Tourneau, Inc. is offering a $40,000 reward for information leading to the recovery of the stolen watches.

Anyone with information is asked to contact the Upper Merion Police Department at 610-265-3232.