Charter Communications Inc. said late Saturday that the company was aware of some customers experiencing Internet outages across its service area.

Charter spokeswoman Kim Haas says the company is working to restore service and says the cause is unknown. She said the issues were “intermittent across parts of our footprint.”

Haas said she could not provide any further details.

Social media users posted complaints on the company’s Twitter and Facebook pages. The company did not immediately respond on either site.

Numerous calls to the company’s customer support number rang busy.

Stamford, Connecticut-based Charter is the fourth largest cable operator in the U.S., according to its website. It also provides phone services and serves customers in 29 states