BOSTON (AP) — The FBI and two federal agencies say cybercriminals are unleashing a major ransomware assault against the U.S. healthcare system. Independent security experts say it has already hobbled at least four U.S. hospitals this month, and could potentially impact hundreds more. In a joint alert, the FBI and two federal agencies say they have credible information of an imminent cybercrime threat to U.S. hospitals and healthcare providers. They say malicious groups are targeting the sector with ransomware that could lead to data theft and disruption of healthcare services. The attacks do not appear to have any connection to the U.S. presidential election.