LOS ANGELES (AP) — U.S. immigration agents descended on dozens of 7-Eleven stores before dawn Wednesday to open employment audits and interview workers in what officials described as the largest operation against an employer under Donald Trump’s presidency.

Agents targeted about 100 stores nationwide, broadening an investigation that began with a 4-year-old case against a franchisee on New York’s Long Island. The audits could lead to criminal charges or fines over the stores’ hiring practices.

The action appears to open a new front in Trump’s sharp expansion of immigration enforcement, which has already brought a 40 percent increase in deportation arrests and plans to spend billions of dollars on a border wall with Mexico. Hardliners have been pressing for a tougher stance on employers.

Derek Benner, a top official at U.S. Immigration and Customs Enforcement, told The Associated Press that Wednesday’s operation was “the first of many” and “a harbinger of what’s to come” for employers. He said there would be more employment audits and investigations, though there is no numerical goal.

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