After experiencing problems for several hours, the crucial payment system, known as Fedwire, resumed normal operations shortly before 3 p.m. ET, according to the Fed's website.

Other Fed services are still down, however.

In a statement, the Fed blamed an "operational error" and said it is working to restore services and communicate with customers.

Banks, businesses and government agencies rely on Fedwire to transfer vast sums of money around the US banking system. More than $3 trillion was transferred daily using Fedwire during the fourth quarter.

The problems were widespread. Fed staff "became aware of a disruption for all services" beginning around 11:15 a.m. ET, according to a message on the Fed website.

"Our technical teams have determined that the cause is a Federal Reserve operational error," the message said.

In an update, the Fed said that it has "taken steps to help ensure the resilience" of Fedwire and national settlement service applications "including to the point of failure."

It's not clear how many banks or companies are affected by the outage.

Gemini, the cryptocurrency exchange backed by the Winklevoss twins, said some of its systems are experiencing outages because of the Fed disruption. "All funds remain secure while we investigate the issue," Gemini said in a status update.

A person familiar with the matter at a major bank told CNN Business that Fedwire flows have resumed. There are few concerns that any payments will fail to be executed due to the outage, the person added.