Thousands of diagnostic appointments, cancer treatment clinics and surgeries have been canceled or delayed since Friday’s cyberattack. Authorities said hundreds of people were assigned to get crippled systems back online, but it could be weeks before the public health service will return to normal.

Irish Prime Minister Micheal Martin said the attack was a “heinous” one that targeted patients and “the Irish public.” The chief clinical officer of Ireland’s Health Service Executive, Colm Henry, said the intrusion was having “a profound impact on our ability to deliver care” and that disruptions would undoubtedly “mount in the coming days and weeks.”

More than 2,000 patient-facing IT systems were affected, and around 80,000 devices were linked to such systems throughout the health service, Henry told Irish broadcaster RTE. Authorities are prioritizing the recovery of systems involved in patient diagnostics, such as radiology, radiotherapy and maternity and newborn services.