Transportation Secretary Pete Buttigieg said Thursday that the ransomware attack on Colonial Pipeline, the operator of the country’s largest fuel pipeline, has been a “wakeup call” for U.S. cybersecurity vulnerability.

Colonial is still struggling with a cybersecurity attack that forced its entire system offline on Friday and triggered widespread fuel shortages across the East Coast. The company restarted operations Wednesday afternoon but said the system won’t return to normal for several days.

“This has been a wakeup call on how actors anywhere in the world can impact us right here at home,” Buttigieg said during an interview on CNBC’s “Squawk Box.” He added that the all-of-government response to the hack has “really paid off.”

Buttigieg’s remarks come a day after President Joe Biden signed an executive order to help strengthen U.S. cybersecurity defenses.

The president’s order calls on the federal government and private sector to work together to combat “persistent and increasingly sophisticated malicious cyber campaigns” that threaten the U.S.

The Department of Energy has led the federal response to the attack in coordination with the F.B.I., the Department of Homeland Security and the Department of Defense.

Buttigieg said the response has included weight limit waivers for tank trucks to help ease shortage concerns, as well as increased flexibility in allowing workers to conduct manual inspections.

Biden Energy Secretary Jennifer Granholm said Thursday morning that Colonial’s pipeline restart “went well overnight.”

“This should mean things will return to normal by the end of the weekend,” Granholm wrote in a tweet.

Colonial’s shutdown led to panic buying in some states and p

ushed the national average for a gallon of gas above $3 for the first time since 2014.

Colonial shut off its system as a proactive measure after falling victim to the attack by a cyber criminal group known as DarkSide. The company’s pipeline spans 5,500 miles and carries almost half of the fuel supply on the East Coast, including gasoline, diesel fuel, heating oil and jet fuel.

Gas outages continue to hit the Southeast, with more more than half of stations in South Carolina, North Carolina and Virginia without fuel, according to the latest data from GasBuddy.

— CNBC’s Pippa Stevens contributed reporting