Comcast said Friday that the hours-long interruption of its internet, video and voice services, was caused by two separate and unrelated fiber cuts to the company's large network providers. The company is working to restore services.

“We identified two, separate and unrelated fiber cuts to our network backbone providers. Our engineers worked to address the issue immediately and services are now being restored to business and residential internet, video and voice customers. We again apologize to anyone who was impacted.”

The company did not specify which providers were impacted.

A source told CNBC that one of the cuts occurred in CenturyLink's network.

CenturyLink said its network is operating normally, but said there were fiber cuts in its network Friday.

“While the CenturyLink network continues to operate normally, on June 29, we experienced two isolated fiber cuts in North Carolina affecting some customers that by themselves did not cause the issues experienced by other providers. At this time, our technicians are working to restore the services,” the company said in a statement.

Comcast reported last quarter it serves 29.6 million total business and residential customers. It is the second largest U.S. pay TV provider, behind AT&T, since its DirecTV acquisition,.

Disclosure: Comcast is the owner of NBCUniversal, parent company of CNBC and CNBC.com.