Comcast tweeted that "One of our large backbone network partners had a fiber cut", which is impacting several services.
The company directed customers to try its status center online and said crews were working to restore service.
Customers in Seattle, Portland and Spokane also had reported outages.
The company replied to some Twitter users complaining about the lack of service.
Cable giant Comcast and its Xfinity cable service suffered a massive outage on Friday.
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The Comcast issues we were experiencing earlier today have been resolved, and the number of downdetector.com reports is dropping. The page was where customer service directed many disgruntled customers, which would require an internet connection many did not have.
"It is now affecting our business and residential internet, video and voice customers", the company said. Customers in some areas such as Pittsburgh and Chicago are reporting that service has come back up.
Other Pennsylvania cities included York, Lancaster and Harrisburg. Internet service was not affected.
Many people in the Shenandoah Valley have very limited options when it comes to their internet provider, with Comcast being one of - if not the only - options.