All three platforms stopped working shortly before noon ET, when the websites and apps for Facebook’s services were responding with server errors. Reports on DownDetector.com showed the outages appeared to be widespread, but it was unclear how many users were unable to access the apps.

ThousandEyes, a network monitoring service owned by Cisco, said in an email that the outage was the result of DNS failure. DNS, short for Domain Name System, is like a phone book for websites.