The Colonial Pipeline is the largest refined products pipeline in the United States, carrying 100 million gallons of fuel per day from refineries in the Gulf Coast to markets along the East Coast. On May 7, the pipeline was hit by a ransomware attack that forced it to shut down operations.

The attack created a fuel shortage and panic buying across the Southeast, as drivers rushed to fill up their tanks before prices spiked.

The ransomware used in the attack, known as Darkside, encrypted Colonial’s computer systems and demanded a ransom of 75 Bitcoin, or about $4.4 million, to decrypt them.

Colonial initially said it would not pay the ransom, but on May 10, the company announced that it had made the decision to pay the attackers in order to get the pipeline up and running again as quickly as possible.

Critics have questioned whether paying the ransom was the right decision, as it could encourage other ransomware gangs to Target critical infrastructure. However, experts say that Colonial likely had little choice in the matter, as the alternative would have been a lengthy and costly shutdown of the pipeline.