The company's Elastic Cloud Compute (EC2) has "degraded performance for a small number of EBS [Elastic Block Store] volumes in a single Availability Zone" in the North Virginia Zone.
As a result, sites including Reddit, Minecraft, Foursquare, Flipboard and Airbnb have experienced downtime today (October 22).
"The site is down right now. It appears to be a network-related issue. We are investigating," Reddit tweeted.
All services hosted on Heroku's virtual private servers are down at the time of writing. GitHub, imgur, Pocket, HipChat, Coursera and others are affected, TechCrunch reports.
The issue is also said to be affecting other parts of Amazon Web Services. Amazon's RDS database instances and Elastic Beanstalk are now down in North Virginia.