Having trouble accessing Facebook or Instagram on Wednesday? You weren't alone. 

The massively popular social network started having problems at around noon Eastern time, with issues popping up across Facebook proper, Facebook Messenger and Instagram around the world. The service outage is one of the longest Facebook has ever experienced.

After being out much of Wednesday, Facebook began to come back to life early Thursday morning after midnight ET for many users.

As of publication, service had not yet been fully restored, but some users are able to access it more than others.

Rob Leathern‏, Facebook director of product, tweeted early Wednesday afternoon that officials were “also aware that people are experiencing issues with access to our ads interfaces, we'll share an update as soon as possible.”

Around 9:30 p.m. Leathern tweeted “I don’t have any update yet :(“

A Facebook spokesperson told USA TODAY that as of 10 p.m. ET, there's no update on when the service will be fully restored.

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It is also not clear what caused the issue, leading to confusion and speculation. 

Roland Dobbins, an engineer with network performance firm Netscout said Wednesday that the outage was due to an accidental traffic jam issue with a European internet company that collided with Facebook and other websites.

"While not malicious in nature, such events can prove disruptive on a widespread basis," he said.  

ThousandEyes, a firm that helps companies optimize their traffic, refutes Netscout's assessment, saying that in its analysis the outage appears to be an "internal" problem for Facebook "rather than a network or Internet delivery issue."