Amazon announced Monday it will deliver packages by drone to Lockeford, California residents by the end of the year. It will be the first time the online retailer will use drones to deliver packages to customers.

In a release on its website, Amazon said the company started working years ago to develop a sense and avoid system which allows the drones to operate without visual observers. Most drones do not have the ability to avoid obstacles on their own and require someone to physically observe the drone while in operation.

The sense and avoid system gives Amazon drones a larger delivery radius and makes sure the drones don’t crash into things like planes, chimneys, or power lines when in the air. The system even detects pets in the landing zone. If an object is detected, the drone will automatically change course to safely avoid a collision.

Amazon said it tested more than two dozen prototype delivery drones before landing on its current design, the mk27-2. Amazon said hundreds of scientists, engineers, aerospace professionals, and futurists have worked on making Prime Air deliveries a reality.

Once Prime Air officially takes off in Lockeford, customers can shop online for Prime Air eligible items. Amazon teams will work with customers to track feedback. The company said it wants to “create a service that will safely scale to meet the needs of customers everywhere.”