Facebook appeared to still be inaccessible for several users on Thursday after many account holders across the globe reported that the social media website and app were down the previous evening. While some users complained that they were having trouble posting on the social media site, others said they were not able to log in at all. Facebook-owned photo-sharing platform Instagram too reported issues.

A message showing to some of the users said that Facebook is down due to scheduled maintenance. “Facebook will be back soon,” the message showing to users reads. “Facebook is down for required maintenance right now, but you should be able to get back on within a few minutes. In the meantime, read more about why you’re seeing this message. Thanks for your patience as we improve the site.”

The BBC described the situation as the “most severe outage” in Facebook’s history.

Several users said that their attempts to use Facebook to log into apps including Tinder or Spotify were obstructed too, The Verge reported.

Facebook and Instagram took to Twitter to reassure its users. “We are aware that some people are currently having trouble accessing the Facebook family of apps,” their statements said, while ruling out the possibility of a distributed denial-of-service cyber attack. “We are working to resolve the issue as soon as possible.”

A distributed denial-of-service attack occurs when multiple systems flood the bandwidth of a particular system.

Users reported seeing “error code 1” and “error code 2” while trying to log into Facebook.
Website DownDetector said the errors were reported in parts of the United States, the United Kingdom, India, and the Philippines.

Several social media users took to Twitter to express their dismay and in some cases, panic.