Photo via Amazon Fresh.

Photo via Amazon Fresh. may add a fleet of delivery vehicles and has begun testing the initiative in the San Francisco area, as the online retailer moves toward same-day delivery, reports the Wall Street Journal.

Amazon is considering a lease for a Treasure Island facility that could serve as a hub for deliveries into San Francisco. The retailer already operates a fleet of Amazon Fresh delivery trucks that provide same-day and early morning delivery ofgrocery items, everyday essentials, and local products.

The delivery fleet would bring fresh competition to FedEx Corp., the United Parcel Service and the U.S. Post Office. Other retailers including Wal-Mart, eBay, and Google are also testing deliveries, the Journal reports.

UPS and FedEx were overwhelmed by holiday commerce in late December, when they experienced delays and consumer complaints amid a spike in online ordering.