Colonial Pipeline,a huge network that supplies eastern states with gasoline, diesel and other products, is shut down thanks to a major ransomware attack disclosed over the weekend.

Why it matters: Colonial is the largest refined products pipeline network in the country, transporting over 100 million gallons per day.

The company provides roughly 45% of the fuel used on the East Coast, per its website and published reports.

• "It’s the most significant, successful attack on energy infrastructure we know of in the United States," veteran energy analyst Amy Myers Jaffe tells Politico.

What's new: The company said Sunday evening that while the main portions of the pipeline remain offline, "smaller lateral lines between terminals and delivery points" are back up.

• Gasoline futures are trading higher, but the ultimate effect on prices will depend on the duration of the shutdown.
• Major price increases are not expected if it only lasts a few days.

The big question: That's how long the pipeline will remain down.

• "[An] extended outage would likely see spot retail price spikes and even product shortages in harder-to-resupply middle and southeastern states, especially if there’s hoarding," Rapidan Energy Group said in a note.

What they're saying: Via Reuters, "While the U.S. government investigation is in the early stages, a former U.S. official and three industry sources said the hackers are suspected to be a professional cybercriminal group called DarkSide."

Where it stands: On Sunday the Transportation Department issued a regional emergency declaration in 17 states that enables increased trucking hours to deliver fuel by road.

• The move is designed to "avoid disruption to supply," the agency said. More broadly, Commerce Secretary Gina Raimondo told CBS' "Face the Nation" there's an "all hands on deck" effort to resume operations.