The new store, in Chicago, started its first day of business on Monday, with a busy stream of customers scanning an app on their smartphones when they enter the store and then leaving without having to go through check out. Instead, Amazon uses scanners and cameras to tabulate purchases and then automatically charges customers when they leave in what the company calls “just walk out shopping.”

Despite the lack of cashiers, the company claims Amazon Go locations won’t completely do away with workers, as staffers are still needed to unload shipments and stock the stores. Amazon Go vice president Gianna Puerini said cashierless convenience is about doing away with the aspects of checkout customers most dislike. “I don’t know a ton of people who say, ‘I love the part where I wait in line and they ring up all my stuff,'” she told the Chicago Tribune.

Before opening its first of three Amazon Go Seattle locations, the company spent more than a year testing the cashierless physical store concept. Part of Amazon founder Jeff Bezos’ plan to dominate not just online but brick-and-mortar retail, Amazon Go joins Whole Foods as the company’s grocery and convenience store portfolio continues to expand. Amazon acquired Whole Foods for $13.7 billion in 2017.

In February, it was reported that Amazon Go will continue its expansion in 2018, with locations opening in several more cities this year, including Los Angeles.