Santa wasn't the only one racing against the clock to get packages to homes Tuesday night. UPS was too.
But the company's backlog left some Americans with gifts missing from under the Christmas tree Wednesday morning.
"We're terribly sorry," spokeswoman Natalie Black told CNN.
In a statement, the company explained that "the volume of air packages in our system exceeded the capacity of our network immediately preceding Christmas so some shipments were delayed."
"We know how hard it is for everyone to receive their holiday packages, and we're working around the clock to resolve this issue," Black said.
Behind the scenes, perhaps -- but UPS stuck to its plan to make no deliveries on Christmas, angering some customers.
Online retailers are damaged by UPS' mistake. These sites told customers their purchases would arrive in time for Christmas.
Some customers received messages from Amazon.com alerting them of the "failure in the UPS transportation network." In the message, the company offered to refund shipping charges and provide gift cards.
Amazon released the following statement:
Amazon fulfillment centers processed and tendered customer orders to delivery carriers on time for holiday delivery. We are reviewing the performance of the delivery carriers.