The site notes that the recent reports of outages mostly concern internet connectivity, not television or phone service, and mostly originate from areas like Mountain View, Denver, Portland, New York, Chicago, Seattle, Houston, San Francisco, the Bronx and Minneapolis. Comcast, a major owner of NBCUniversal, does business in 40 states and the District of Columbia. The company has confirmed the issues with its Xfinity internet service, and says that it is working on a fix.
The company just tweeted attributing the outage to an "external network issue." We'll continue to update this post as more information becomes available.
Update: As of about 3:30 PM ET, Comcast has said that its connectivity issues are resolved: