The robbery and shootings occurred about 6 a.m. EST at the Community Market, The Palm Beach Post reported
The robbers, wearing bandannas over their faces, opened fire with semiautomatic handguns when they entered the store. Witnesses told police the men pistol-whipped an employee then took money from the cash register.
Police said there was a similar-style robbery two blocks away Saturday night, the Post said.
Their behavior was "strikingly similar" to a Saturday night robbery less than two blocks away, police said.
The victims' names had not been released.