Loads of UPS customers expressed disappointed Tuesday after many packages failed to arrive on doorsteps in time for Christmas.
USA TODAY reports thousands of shipments by UPS, the world's largest package delivery service, have been delayed due to a higher-than-anticipated volume of air packages.
Company spokeswoman Natalie Godwin told the newspaper that the demand "exceeded the capacity of our network" and is affecting "a small percentage of shipments."
The company would not say exactly how many packages are affected.
According the the Wall Street Journal, UPS estimated its air network would handle about 7.75 million shipments on Monday. About 3.5 million of those packages were expected to be sorted at the company's large Louisville hub, but not all the deliveries could be processed before the holiday.
Since UPS doesn't deliver on Christmas, those who didn't receive their packages on Christmas Eve won't likely see them until Thursday.
A different spokeswoman told CNN that UPS is employing an "all-hands on deck" to get deliveries out.
The company experienced another major slowdown earlier this month after pulling delivery drivers off the roads in Texas due to a dangerous ice storm.
UPS delivers about 26 million packages per day during the holiday season, significantly more than the average 16 million on a typical day.
CNN says UPS planned to make more than 120 million deliveries this week, its busiest of the year.