Friday night’s cyberattack is “the most significant, successful attack on energy infrastructure” known to have occurred in the U.S., according to Politico.

Colonial Pipeline carries 45% of fuel supplies in the eastern U.S. Some 5,500 miles of the pipeline has been shut down in response to the attack.

While gasoline and diesel prices aren’t expected to be impacted if pipeline operations resume in the next few days, fuel suppliers are becoming “increasingly nervous” about possible shortages, Bloomberg reports.

Colonial said in a statement Sunday while its main fuel lines remained offline, some smaller lines between terminals and delivery points were now operational.

He said “We will bring our full system back online only when we believe it is safe to do so and in full compliance with the approval of all federal regulations”

The US said it’s “working with” fuel pipeline operator Colonial Pipeline to try and restart operations as soon as possible.

The regional emergency declaration by the Department of Transportation’s Federal Motor Carrier Safety Administration is so that fuel supply lines can be kept open.

The emergency declaration covers Alabama, Arkansas, D.C., Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Tennessee, Texas and Virginia.

The DoT agency said in a statement the declaration “addresses the emergency conditions creating a need for immediate transportation of gasoline, diesel, jet fuel, and other refined petroleum products and provides necessary relief.”

The attack is a significant breach of critical infrastructure and comes on the heels of multiple other major cyberattacks on both U.S. companies and the federal government in recent months by foreign actors.

Francisco Javier Garcia, speaking at an event Thursday coordinated by the American Chamber of Commerce of the Dominican Republic in New York City, reiterated that the Caribbean island is a safe travel destination for tourists from around the world and particularly for visitors from the U.S., who account for more than 3 million visitors each year.

He said a National Committee of Tourism Security has been established by the Dominican government, focused on monitoring and improving security measures in the tourism poles across the island nation.

The committee includes 16 government agencies, including the military and the national police, along with private entities like the Association of Hotels and Tourism of the Dominican Republic (ASONAHORES).

“Tourism in the Dominican Republic is a model for development (of the industry),” Garcia said through a translator. “More than 50 years of hard work, we have the best installations in the Caribbean — the best infrastructure in the Caribbean region.”

The minister said they also have reinforced rules that now require emergency information and the 911 number be clearly posted in every guest room.

The island’s safety came under scrutiny earlier this year after Tammy Lawrence-Daley of Delaware claimed she was assaulted by a hotel employee at the all-inclusive luxury resort Majestic Elegance in Punta Cana. Her claims were amplified after the deaths of at least nine American tourists in the weeks that followed at various hotels across the country.