A call regarding the robbery in progress at Arka Design Fine Jewelry came in shortly before 3 p.m., authorities said. The store is located in between ballrooms inside the hotel on the main floor.
The suspects, who used a hammer as a weapon, were seen fleeing in a silver Lexus. Authorities said pepper spray was also involved in the crime.
Authorities said a 35-year-old man employed at the shop suffered cuts to his head. Another employee later said that the man's injuries were minor.
"It was so severe. The pepper spray in the air - I'm not kidding - it was terrible. There was a lot of blood on the floor, I thought, and we saw the guy being put onto the gurney," one witness said.
It was unclear what the suspects stole, and no descriptions were provided.
The hotel said it has dozens of cameras, and police believe those will be helpful in their investigation.