Amazon representatives didn’t immediately respond to a request for comment.
The grocery stores represent Amazon’s latest move to disrupt brick-and-mortar food shopping that’s still dominated by traditional retailers such as Wal-Mart Stores Inc.
While Amazon has dominated in e-commerce, convincing customers to shop online for everything from toiletries to electronics, it has yet to crack groceries -- which most consumers still buy offline.
Previously, Amazon had focused on fresh food deliveries rather than establishing a physical presence but it’s encountering increased competition from Google, Instacart and others.
Wal-Mart, whose main selling point has been its physical reach, started a grocery pickup service more than a year ago and has now expanded it to more than 100 markets.
Customers can purchase online, drive to the parking lot of a Wal-Mart store and have their orders delivered to their cars. Even as Amazon uses the Fresh grocery service and Prime membership to keep customers loyal, Wal-Mart is trying to create a better online experience.