When attempting to access the App Store, users are receiving a message that it can't be reached, while Apple Music says "We've run into a problem" when attempting to access the For You or Browse features. As for iTunes, streaming iTunes content was interrupted and can't be reaccessed.
The outage appears to be affecting Apple customers in multiple countries, including the United States, the UK, and Germany. Given the volume of reports, most if not all users seem to be unable to access Apple's services.
Apple's System Status page is not reporting an outage at this time, and it is not known how long Apple's services will be down for. We'll update this post when the App Store, iTunes, Apple Music and other features are once again functional.