The Colonial Pipeline, the main conduit carrying gasoline and diesel fuel to the U.S. East Coast, said it had halted all operations after being hit with a cyberattack.

Colonial Pipeline Co., which operates the 5,500-mile system taking fuel from the refineries of the Gulf Coast up to the New York metro area, said it learned Friday that it was the victim of the attack and “took certain systems offline to contain the threat, which has temporarily halted all pipeline operations.”

The company said it had engaged a third-party cybersecurity firm to help with the issue, which affected some of its IT systems, and had contacted federal agencies and law enforcement.

The Colonial Pipeline is the largest refined-products pipeline in the U.S., transporting more than 100 million gallons per day, or roughly 45% of fuel consumed on the East Coast, according to the company’s website. It delivers fuels including gasoline, diesel, jet fuel and heating oil, and also serves U.S. military facilities.

“At this time, our primary focus is the safe and efficient restoration of our service and our efforts to return to normal operation,” the company said in its statement. “This process is already underway, and we are working diligently to address this matter and to minimize disruption to our customers.”