NEW YORK -- The online delivery wars are heating up inside shoppers' homes.

Walmart is now offering to have one of its employees deliver fresh groceries and put them in your refrigerator when you're not home.

The nation's largest grocer said Friday that it will be offering the service this fall for more than one million customers in three cities: Pittsburgh, Kansas City, Missouri, and Vero Beach, Florida. Later this year, the service, called InHome Delivery, will also accept returns for items purchased on Walmart.com.

Two years ago, Walmart tested a similar service in the Silicon Valley area but teamed up with delivery startup Deliv and worked with August Home, makers of smart locks and smart home accessories. That test has since been stopped.

The new service is part of Walmart's drive to expand its shopping options that include curbside pickup and online grocery delivery.

Amazon offers a similar service in certain cities, dropping off packages inside homes, garages or car trunks. But the service is not for groceries.

With Walmart's new service, customers place a grocery delivery order online and then select InHome Delivery and a delivery day at checkout.

Walmart workers will use smart entry technology and a proprietary wearable camera to access the customer's home. That allows shoppers to control access into their home and give them the ability to watch the delivery remotely.

Walmart said that the workers will go through an extensive training program that would prepare them for things like how to select the freshest groceries and how best to organize the refrigerator. Walmart declined to give specifics on the technology. It said it will share the fee details ahead of the fall launch.

"Now, we can serve customers not in just the last mile, but in the last 15 feet," wrote Marc Lore, CEO of Walmart's U.S. e-commerce division, in a corporate blog post.

With Amazon's service, customers need to be an Amazon Prime member and they have to buy a camera and a Wi-Fi-connected lock from the Seattle-based company that starts at $250. Shoppers will then be able to select in-home delivery on the Amazon app. When the delivery person shows up, he or she will knock first and scan the package, then Amazon will make sure the delivery person is at the right home and unlock the door. No codes are needed and the indoor camera will record the in-home delivery.