The heist happened on Monday night at a store inside the Borgata Hotel and Casino.
Police say there was just one clerk in the store when the suspects entered and smashed two cases.
Surveillance cameras captured three men making off with luxury brand watches.
The entire robbery took just a few minutes.
All three are said to be African American men, one wearing a blue jacket, one a grey hooded sweatshirt, and one in a dark colored jacket.
During a Tuesday afternoon news conference, police said they were making progress in the case.
Police are also investigating whether this robbery is connected to other smash-and-grab robberies in the area.
The robbery was the buzz on the Atlantic City Boardwalk.
Peter Levanti of Connecticut reacted to news of the heist by saying, "I just can't believe somebody would actually do something like that."
Diane Morales of Allentown said "I'm surprised they could get out that quick." She added, "It's not like it's on the boardwalk and you can just run."
Anyone with information is urged to call Atlantic City Police Department Criminal Investigations Unit at 609-347-5766.