The website said the problem started just after 12:30 p.m. Friday.
The outage, triggered by cut fiber lines, brought down internet, television and phone service for Comcast XFINITY customers in markets including NY and Philadelphia.
Cable giant Comcast Corp.is responding to a widespread outage Friday that has left customers without cable, internet and phone services in several areas around the country.
According to various statements provided by Comcast through the Comcast Cares Twitter account, the company now has no timeline for when services may be restored.
A major outage is affecting Comcast customers nationwide, including throughout the Shenandoah Valley.
Comcast's verified Twitter account replied to some users complaining about a lack of service.
The company apologized for the disruption and said it is "working to get services restored as soon as possible".
A Comcast sign is seen as the US media group submitted a $30.7 billion bid for Sky on April 25 in Miami. The company is the largest cable service provider in the United States.