Petrol stations from Florida to Virginia have begun running dry, with prices at the pump jumping as the shutdown of the biggest US fuel pipeline by hackers extends to a fifth day.
The shortage has sparked panic buying by motorists.
About 7.5 per cent of petrol stations in Virginia and 5 per cent in North Carolina had no fuel on Tuesday local time as demand jumped 20 per cent, tracking firm GasBuddy said.
Prices rose to their highest in more than six years, and Georgia suspended sales tax on petrol until Saturday to ease the strain on consumers.
North Carolina declared an emergency.
Driver Caroline Richardson said she was paying 5 cents more per litre than a week ago as she refueled at a station in Sumter, South Carolina.
“I know some friends who decided not to go out of town this weekend to save gas,” she said.
Colonial Pipeline forecast it would not substantially restore operations of the 8,900-kilometre pipeline network that supplies nearly half of the East Coast’s fuel until the end of the week.
The company preventively shut the pipeline on Friday after hackers locked its computers and demanded ransom, underscoring the vulnerability of US energy infrastructure to cyber attack.
The strike on Colonial “is potentially the most substantial and damaging attack on US critical infrastructure ever,” Ohio senator Rob Portman told a Senate hearing on cybersecurity threats on Tuesday.
Unleaded petrol neared an average $1 a litre, its highest price since November 2014.
The American Automobile Association urged consumers not to hoard, saying it would worsen shortages.
Hackers believed to be in Eastern Europe
The FBI has accused a shadowy criminal gang called DarkSide of carrying out the ransomware attack.
DarkSide is believed to be based in Russia or Eastern Europe and avoids targeting computers that use languages from former Soviet republics, cyber experts say.
Ransomware is a type of malware designed to lock computers by encrypting data and demanding payment to regain access.
Russia’s embassy in the United States rejected speculation that Moscow was behind the attack.
President Joe Biden a day earlier said there was no evidence so far that Russia was responsible.
A statement issued in DarkSide’s name on Monday said: “Our goal is to make money, and not creating problems for society.”
It is unknown how much money the hackers are seeking, and Colonial has not commented on whether it would pay.
“Cyber attacks on our nation’s infrastructure are growing more sophisticated, frequent and aggressive,” Brandon Wales, acting director of the Cybersecurity and Infrastructure Security Agency (CISA), said on Tuesday at a Senate hearing on the SolarWinds hack that hit companies and government agencies.
Government steps in to help ease crisis
The Environmental Protection Agency issued a waiver on Tuesday that allows distributors to continue supplying winter fuel blends through May 18 in three Mid-Atlantic states to help ease supplies.
North Carolina and the US Department of Transportation, meanwhile, relaxed fuel-driver rules, allowing truckers hauling petrol to work longer hours.
There are growing concerns that the pipeline outage could lead to further price spikes ahead of the Memorial Day weekend at the end of this month.
The weekend is the traditional start of the busy summer driving season.