A nationwide cyberattack has crippled operations at Universal Health Services, one of the nation’s largest health care providers. As a result, health care personnel reportedly began keeping records on paper as computer systems began failing over the weekend and some hospitals have sent incoming ambulances to other neighboring hospitals.

Universal Health Services posted an update on the situation Monday morning on its website stating the IT network across its facilities was offline due to “an IT security issue.” The King of Prussia, Pennsylvania-headquartered health care giant’s operations include 26 acute-care hospitals, 328 behavioral health facilities, and 42 outpatient facilities across the U.S., Puerto Rico and the U.K.

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