Amazon.com began testing the first lot of its Rivian Automotive electric delivery vans in Los Angeles as it works to fulfill a pledge to meet the goals of the Paris climate accord 10 years early.

The Seattle-based e-commerce company plans to expand the program to 15 more cities this year, it said in a blog post. Amazon, which is backing Rivian along with Ford Motor, is buying 100,000 electric vans that are custom-built for Amazon Prime. The first vehicles were due to start making deliveries this year.

Rivian recently raised $2.65 billion in new funding from a group of investors led by T. Rowe Price Group, and is one of a number of startups trying to bring new electric vehicles to market and take on incumbent Tesla, whose shares skyrocketed last year. Rivian plans to build a full-size battery-powered sport-utility vehicle and truck at a plant in Normal, Illinois, a retooled former Mitsubishi Motors factory.