Four masked men, one of them armed with a hammer, walked into a watch store at the Pentagon City mall, smashed a display case and grabbed almost two dozen Rolex watches valued at $609,000, according to Arlington police.

It happened Tuesday morning just after 10:30 a.m. at the Torneau store at Fashion Centre at Pentagon City. The men had masks covering their faces, hoods and gloves on their hands, said Dustin Sternbeck, spokesman for Arlington County police.

The thieves walked into the mall at the South Hayes Street entrance, near the store, shattered a display case with a hammer and grabbed the watches. Then they ran to a waiting car, described as a gray, four-door sedan, Sternbeck said.

He said the hammer had a yellow handle and looked like a carpenter’s tool.

Nobody was injured in the robbery, and police said the men did not say anything as they pulled off the heist. There was one employee in the front of the store who was about to clean display cases when the robbery happened. He began yelling for help as soon as he saw the masked men enter the store, Sternbeck said.

Police are investigating whether the incident is connected to a similar smash-and-grab at the mall days before Valentine’s Day, when men armed with hammers smashed a display case at a Zales jewelers and scooped up more than two dozen diamond rings valued at $128,000.

“We just don’t know if they’re connected,” Sternbeck said. “It’s too early on.”

Investigators were reviewing video footage of the incidents.