Seven immigration agents filed into a 7-Eleven store before dawn Wednesday, waited for people to go through the checkout line and told arriving customers and a driver delivering beer to wait outside. A federal inspection was underway, they said.

Within 20 minutes, they verified that the cashier had a valid green card and served notice on the owner to produce hiring records in three days.

The well-rehearsed scene, executed with quiet efficiency in Los Angeles’ Koreatown, played out at about 100 7-Eleven stores in 17 states and the District of Columbia, a rolling operation that officials called the largest immigration action against an employer under Donald Trump’s presidency.

In Maryland, seven 7-Eleven stores were targeted. One was in Baltimore, while the others were in Landover, Pasadena, Upper Marlboro, Glen Burnie, Severna Park and Frederick, according to an U.S. Immigration and Customs Enforcement spokesman.