Businesses are rushing to contain a ransomware attack that has paralyzed their computer networks, a situation complicated in the U.S. by offices lightly staffed at the start of the Fourth of July holiday weekend. In Sweden, public broadcaster SVT says most of the grocery chain Coop’s 800 stores were unable to open because their cash registers weren’t working. The Swedish State Railways and a major local pharmacy chain are also affected. Cybersecurity experts say the REvil gang, a major Russian-speaking ransomware syndicate, appears to be behind the attack that targeted a software supplier called Kaseya.