Various websites that track Gmail problems and outages, showed a spike in users reporting problems with the email service from about 2am United Kingdom time.
A Facebook spokesman, asked by Reuters for more details, would only repeat the company's initial statement on the outage on Wednesday, saying that it was working to resolve the issue as soon as possible.
Facebook posted to Twitter reassuring users that the site would be back online.
Facebook is experiencing the worst outage in its history, with essential services left unusable for global users.
Facebook took to rival social network Twitter to communicate with users about the outage.
"You make it sound as if it's the end of the world just because you can't be on Facebook".
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A short time later, Facebook indicated the outage was not related to an attack aimed at overwhelming the network.
Facebook did not say what was causing the outages. Users reported problems that they can neither access to the website, nor post on it.
On its developer site, Facebook said: "We are now experiencing issues that may cause some API requests to take longer or fail unexpectedly".
Some Twitter users who work in "Facebook-centric" jobs, expressed their panic and distress at being unable to use the platform.
Facebook's main product, its two messaging apps and image-sharing site Instagram were all affected.
Outages reportedly began around noon Eastern time on Wednesday afternoon.
The issues affected users around the globe, with people in the US, Europe, Asia, Australia, and South America reporting problems.