Swathes of social media users were left frustrated after being unable to access Facebook on Wednesday afternoon.
Huge numbers of people posted problems with the website just after 4pm, with news feeds struggling to load.
Instagram users also faced problems with the app.
Down Detectors has recorded a huge spike in reports of Facebook outages today.
The hashtag #Facebookdown has been trending on Twitter.
A Facebook spokeswoman said: “Earlier today, a networking issue caused some people to have trouble accessing Facebook services.
“We quickly investigated and started restoring access within about an hour, and we have nearly fixed the issue for everyone.
“We’re sorry for the inconvenience.”
Naturally, many people took to Twitter to query what was wrong with Facebook (and express their anguish through gifs).
— Shayla Raquel (@shaylaleeraquel) October 11, 2017
— Bump Bundle (@Bump_Bundle) October 11, 2017
— Grant Cardone (@GrantCardone) October 11, 2017
— Jeff Muñoz (@jmunoz614) October 11, 2017
— Todd Carruth (@toddcarruth) October 11, 2017
— Fern Photography (@AmberFernPhoto) October 11, 2017
When you finally open Twitter just for checking "is facebook down?"
— nesia c (@NesiKa11) October 11, 2017
More to follow.