Facebook, Instagram and WhatsApp – three major social media services – on Tuesday were hit by a massive outage impacting tens of millions of users around the world, including Australia.

Outage tracker Downdetector showed outages in major cities such as Sydney, Melbourne, Athens, New York, Washington, London and Paris. The outage in Athens began at 6.30pm Monday (local time).

“We’re aware that some people are having trouble accessing our apps and products,” the official Twitter account of Facebook said, in its only public comment so far, adding that it was working on restoring access.

We’re aware that some people are having trouble accessing Facebook app. We’re working to get things back to normal as quickly as possible, and we apologize for any inconvenience.

— Facebook (@facebook) October 4, 2021

Instagram head Adam Mosseri tweeted that it feels like a “snow day”.

Facebook CEO Mark Zuckerberg’s personal wealth fell by nearly $US7 billion ($9.6 billion) in a few hours.

It is still unknown what caused the outage of the Facebook platform and its other platforms which began at around 2.45am AEDT Monday.

The sites which went down run oin a shared infrastructure and are still down at this time, however reports point to the problem being on the way to being fixed.

How Facebook , Twitter , Snapchat , Gmail , WhatsApp, Tiktok and Instagram all started having issues at the same time pic.twitter.com/4PgdZjmJnY

— Rich (@UptownDC_Rich) October 4, 2021