More than 45,000 people registered their drones in the two days after the Federal Aviation Administration opened the registry to the public.

The FAA announced those numbers in a notice Wednesday about the registry going offline "in advance of an expected rush of customers on Christmas Day."

Overall, the FAA believes that around 400,000 drones could be sold during the holidays. All of them weighing over 0.55 pounds must be registered, which involves paying $5 and sharing a name, email address and home address with the federal government.

Related:Fail to Register Your Drone? You Could Be Hit With $27K Fine

In return, people get an identification number, which they are expected to affix to every drone that they own. The FAA hopes to use the registration requirement to educate the public about drone safety. Last year, a number of high-profile incidents — including drones that stopped emergency workers from fighting several California wildfires and coming too close to manned aircraft — worried public officials.

The registry comes before more comprehensive regulations that are expected to be put in place early next year.

The FAA said that because an "overwhelming number of people have successfully registered," the agency had "received reports from a small number of users of performance issues" with the online registration site.