The sole communications cable to the Northern Marianas has broken, cutting all phone, internet, banking and other communication with the outside world.
The Pacific Daily News says the fibre-optic cable outage has also affected credit card and ATM systems on Saipan, Tinian and Rota
The territory's telecommunications company, IT&E, says the undersea cable between CNMI and Guam went out shortly after midnight on Wednesday, and the full extent of the damage won't be known for a few days.
Until a backup system is in place, the only communication with Saipan is through a few satellite phones at certain government agencies.
The chief executive of Guam-based Pacific Telecom Inc., IT&E's parent company, James Oehlerking, has apologised for the fault, saying the company is doing all it can to restore services.
"Sorry for the inconvenience and disruption in service that this has provided and we are committed to do whatever is required by IT&E, both in effort and expenditure to minimise the impact of this outage.
The magnitude of the outage to the CNMI's tourism-based economy is unknown, with residents and tourists without access to card transactions and cash from ATMs.