MELVILLE, N.Y. – Dozens of federal agents fanned out on Long Island at dawn Monday seeking to arrest owners and managers of about 10 7-Eleven convenience stores on charges of knowingly concealing and employing undocumented workers, as part of a nationwide sweep involving hundreds of agents, sources said.

The targets on Long Island also are charged with making more than $150 million by cheating the undocumented employees out of much of the salaries they were entitled to and profiting by running their stores illegally, the sources familiar with the investigation said.

The raids are part of a much larger national investigation, coordinated by federal officials on Long Island and involving Immigration and Customs Enforcement agents raiding a number of 7-Elevens in other states, including Virginia, to determine the legal status and employment conditions of employees there, the sources said.

While undocumented workers may be picked up for questioning, no criminal arrests are planned against them, except possibly for being in the country illegally, the sources said.

Officials are also investigating whether leaders of the scheme actively recruited employees under false pretenses, and then helped smuggle them into the United States, sources said. If this turns out to true, it could lead to more charges, including allegations of forcing people into involuntary servitude, the legal term for slavery, the sources said.

"As set forth in the indictments, the defendants used 7-Eleven as a platform from which to run elaborate criminal enterprises," said U.S. Attorney Loretta Lynch. "From their 7-Eleven stores, the defendants dispensed wire fraud and identity theft, along with Slurpees and hot dogs. In bedroom communities across Long Island and Virginia, the defendants not only systematically employed illegal immigrants, but concealed their crimes by raiding the cradle and the grave to steal the identities of children and even the dead.

"Finally, these defendants ruthlessly exploited their immigrant employees, stealing their wages and requiring them to live in unregulated boardinghouses, in effect creating a modern-day plantation system."

The government seized the 10 or so 7-Elevens on Long Island allegedly involved in the case, most of them in Suffolk County, and several more stores in Virginia that are owned and operated by the same people targeted on Long Island, the sources said.

"The defendants have been exploiting vulnerable individuals who, due to their immigration status, may have been afraid to come forward and report possible wrongdoing by their employers," said Suffolk County Police Commissioner Edward Webber. "This multiagency investigation illustrates our commitment to fighting against employers who abuse immigrant employees for their own financial gain."

The company issued a brief statement saying: "7-Eleven is aware of today's activity and has been cooperating with federal authorities during their investigation. … We will have no further comment until we learn more."

The charges will include allegedly harboring illegal aliens, and fraud, for illegally pocketing part of the employees' salaries, the sources said. Other charges may involve identity theft, for using the names and Social Security numbers of unsuspecting real people to help collect some of the pay of the undocumented employees, the sources said.

Many of the undocumented workers were held in conditions, if not that of slavery, something close to it, the sources said.