SEATTLE, Wash. (AP) — Amazon has opened its first cashierless supermarket in Seattle.

At the new Amazon supermarket shoppers can grab milk or eggs and walk out without waiting in line or ever opening their wallets.

First, shoppers scan a smartphone app to enter the store.

Then cameras and sensors track what’s taken off shelves and the items are charged to an Amazon account after leaving.

It’s the latest sign that Amazon is serious about shaking up the $800 billion grocery industry.