In the wee hours of Monday night/Tuesday morning, Twitters users reported that both Facebook and Instagram had gone offline.

Welcome to #SocialMeltdown2015.

One word crossed the minds of night owls: Hacked?

Time for Guess the Culprit. Place your bets:

Keep calm. Or not:

Hah:

Update: Hacker group ‘Lizard Squad’ claims credit.

Update 2:30am Eastern. Facebook and Instagram are back up.

Twitchy readers for the win:

Editor’s note: Tweets were added to this post.