 -- Thousands of tourists had to evacuate two islands along the hugely popular Outer Banks in North Carolina after a construction company caused a massive power outage.

The Cape Hatteras Electric Cooperative said in a press release that PCL Construction told the cooperative it had accidentally driven a steel casing into an underground electric transmission cable while working on the new Bonner Bridge on North Carolina's coast Thursday morning, cutting off power to Ocracoke and Hatteras islands.

Local officials ordered a mandatory evacuation for all visitors on Hatteras Island effective at 6 a.m. ET Saturday. The evacuation order includes the villages of Rodanthe, Waves, Salvo, Avon, Buxton, Frisco and Hatteras, according to ABC station WTVD.

Earlier in the week, local officials ordered a mandatory evacuation for all visitors on Ocracoke Island effective at 5 p.m. ET Thursday.

As of Saturday afternoon, the North Carolina Department of Transportation's ferry division had transported close to 3,800 people and 1,485 cars from both islands, the state governor's office said.

“Ensuring the safety of residents and visitors is our primary concern, but we know the loss of power has a significant economic impact as well,” Gov. Roy Cooper (D-NC) said on Friday. “Summer is the busiest time of year for our North Carolina coastal communities, and we know this outage is causing problems for locals, vacationers and businesses.”

About 35,000 people live year-round in Dare County, where Hatteras Island is located, but during summer months the daily population is estimated to reach 225,000 to 300,000, according to the county website.

People in the area posted photos to social media showing how the darkness and lack of power affected their summer vacations.

The power went out about 4:30 a.m. ET Thursday. Officials said some 9,000 customers are without power on the two islands -- about 7,700 on Hatteras and another 1,300 on Ocracoke, according to The Associated Press.

The governor issued a state of emergency for both islands Thursday night.

PCL Construction said it is working "around-the-clock" with Cape Hatteras Electric Cooperative and state officials to make the necessary repairs to restore power to the islands "as quickly as possible."

"The damage is estimated to be approximately 9 feet below ground level," the construction company said in a statement Saturday. "The crews have recently exposed the affected area and have begun investigating the damage. Electrical experts are currently initiating and assessing options for repairs."