Facebook says it is aware of outages on its platforms including Facebook, Messenger and Instagram and is working to resolve the issue.

According to Facebook’s status page, the outages started around 11 a.m. Wednesday. That page, which calls the problem a “partial outage,” states that Facebook has experienced “increased error rates” since that time.

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

Downdetector.com, a site that monitors site outages, said the Facebook problem affected parts of the U.S., including the East and West Coast; parts of Europe and elsewhere. Both Facebook’s desktop site and app appeared to be affected. Some users saw a message that said Facebook was down for “required maintenance.”

According to the BBC, this is worst outage in Facebook’s history. The last time the social media network had an disruption this big was in 2008. At that time, the site had 150 million users; it has around 2.3 billion monthly users today.

BBC correspondent Dave Lee said the outage is unparalleled.

“The length of time, plus number of users affected, makes this comfortably the most severe outage in Facebook’s history,” he said on Twitter.

Facebook did not say what was causing the outages.

Via its Twitter account, Facebook said the outage was not due to a “distributed denial of service” or DDoS attack, a type of attack that hackers use to interrupt service to a site.