Watch where you step.

Autonomous delivery bots have hit the streets in Washington, D.C., and Redwood City, California, the first two U.S. cities to give the thumbs up to a test run by robotics startup Starship Technologies. According to Recode, the robots started making food deliveries on behalf of Postmates and DoorDash beginning Wednesday.

The robots cruise the sidewalk at 4 mph and navigate using nine cameras, GPS, and artificial intelligence software. They are designed to constantly relay information about their route to the entire fleet, allowing them to travel more efficiently over time.

According to the company, the bots can traverse curbs and small rocks, and they're smart enough to avoid people and animals. To start, an employee will walk alongside them, taking notes on their performance and jumping in should something go awry. Eventually, they'll operate all on their own.

Last year, the company claimed its robots had encountered more than 400,000 people during test runs without a single accident. It's probably inevitable that some people will try to sabotage them, but the 40-pound bots are password protected in an effort to keep the contents safe.

Starship, which has headquarters in the U.K. and Estonia, has already deployed its bots in 40 European cities, including London and several German and Swiss cities. The company tells Inc. it plans to test in Arkansas in the near future.

Founded in 2014 by Skype co-founders Ahti Heinla and Janus Friis, Starship wants to someday use the robots for parcel delivery, either as a last-mile deliverer for postal companies or an on-demand messenger service in urban areas. The startup previously said the cost of such a service averages about $15 in central London, and Starship aims to get that price to around $1.

The company completed a $17.2 million seed round earlier this month that included VC firms Shasta Ventures, ZX Ventures, and Matrix Partners.

Startups like Dispatch and Sidewalk are working on similar delivery robots, but Starship is the first to put its fleet to work in the United States. Restaurant workers will load meals into the robots, which will travel up to two miles per delivery, allowing them to generally arrive within 30 minutes. For now, they'll carry one order at a time.