NEW YORK–One of the nation’s largest financial institutions, Citibank, was hit by an outage that affected millions of people who were unable to access their online banking and credit cards on Tuesday.

Customers who did attempt to access their accounts received a message reading, “We’ve encountered an issue and are working to fix the issue.” They were then told to return in 10 to 15 minutes and directed to a customer service phone.

Downdetector, a site that monitors online outages, showed issues hitting around 10 a.m. ET, with credit cards and mobile banking cited by users as not working, MSNBC reported. Downdetector told the news outlet it had only received a few hundred reports from frustrated customers, with 46% saying they were having issues with their credit cards and 36% saying they could not access mobile banking.

The report further noted that social media accounts were filled with complaints related to the outage.