Amazon is intensifying the last-mile delivery war with its announcement of an ultrafast delivery service, featuring new one-hour and three-hour options.

The new one-hour and three-hour delivery services will be available in 2,000 cities and towns, enabling customers to order from 90,000 items across categories such as groceries, cleaning supplies, health products, electronics, toys, clothing, and home goods.

The service is built into Amazon's existing same-day network, with new search filters, storefront pages, and product labels that make eligible items easier to find.

"The convenience of 1-hour delivery is currently available to customers in hundreds of cities and towns across the U.S., including parts of major metropolitan areas like Los Angeles, Chicago, and Washington, D.C., and smaller cities such as Des Moines, Iowa; Boise, Idaho; and American Fork, Utah," Amazon wrote in a press release.

Prime members pay discounted fees of $9.99 for one-hour delivery and $4.99 for three-hour delivery, while non-Prime customers pay $19.99 and $14.99, respectively.

Amazon's push for one-hour delivery is certainly an acceleration in the last-mile delivery war, as it seeks to gain market share from Walmart Spark, Instacart, DoorDash, Uber Eats, and others.

Shares of Instacart, DoorDash, and Uber were mostly higher in the early U.S. cash market, suggesting the Amazon news has so far gone unnoticed by investors.