Instagram and its parent company Facebook both stopped working for hours today, leaving thousands unable to load the app or visit the website.

People reported being unable to log in or to get into the app, being greeted instead by error messages.

Facebook addressed the problems on its Twitter account:

We’re aware that some people are currently having trouble accessing the Facebook family of apps. We’re working to resolve the issue as soon as possible. — Facebook (@facebook) March 13, 2019

The company later said it was not the victim of a distributed denial-of-service (DDoS) attack:

We’re focused on working to resolve the issue as soon as possible, but can confirm that the issue is not related to a DDoS attack. — Facebook (@facebook) March 13, 2019

Reports of the outages were largely focused across Europe and America’s east and west coasts, according to outage tracking website Down Detector.

The problems came on a busy day for outages, with the world having been hit by significant issues when trying to log in to Gmail and other Google sites earlier in the day.

The outage does not appear to be impacting WhatsApp messages in the United States; however, users in Paraguay, India, Bangladesh, Argentina, and more note that they are experiencing issues with sending messages.

Facebook hasn’t revealed what caused the outage, other than it wasn’t because of a cyberattack.

This isn’t Facebook’s first outage.

In November the social network went down in a mishap caused by a test the company was running.

That outage lasted about 40 minutes.

That same month, Facebook and Instagram were down for hours because of a “server configuration.”