"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."
https://www.usatoday.com/story/tech/talkingtech/2019/03/13/facebook-instagram-go-down-across-united-states-apparent-outage/3151883002/