WASHINGTON (Reuters) — The U.S. Justice Department on Monday said it recovered some $2.3 million worth of cryptocurrency from the Colonial Pipeline Co ransomware attack.

U.S. Deputy Attorney General Lisa Monaco said investigators had seized 63.7 Bitcoins, now valued at about $2.3 million, paid by Colonial after last month’s hack that led to massive shortages at gas stations along the East Coast just as the summer driving season began.

The Justice Department has “found and recaptured the majority” of the ransom paid by Colonial, Monaco said. Colonial Pipeline had said it paid the hackers nearly $5 million to regain access.

Last month, a cyber criminal group that U.S. authorities said operated from Russia penetrated the pipeline operator on the U.S. East Coast, locking its systems and demanding a ransom.

The hack caused a shutdown lasting several days, leading to a spike in gas prices, panic buying and localized fuel shortages in the U.S. Southeast.

The White House urged corporate executives and business leaders last week to step up security measures to protect against ransomware attacks after the Colonial attack and later intrusions that disrupted operations at a major meatpacking company.

Commerce Secretary Gina Raimondo said on Sunday the Biden administration was looking at all options to defend against ransomware attacks and that the topic would be on the agenda when President Joe Biden meets with Russian President Vladimir Putin this month.