ALBUQUERQUE (AP) — A major hospital network in New Mexico was racing to fix a cybersecurity issue on Monday that forced it to send ambulances to other hospitals and left the state without an emergency department capable of treating the most serious injuries.

The University of New Mexico Health System told people not to show up at its main hospital in Albuquerque and has canceled appointments at its more than 30 clinics.

UNM Health System said it was working to resolve the issue, the extent and nature of which was not immediately clear.

The attack comes amid growing concern about the security of digital systems that underpin essential services, from banking to medical care.

UNM's Health Sciences Center, the state's largest academic medical center, is canceling classes and will be closed for the day, the university said.

The hospital network conducts about 900,000 outpatient visits and receives 100,000 emergency room visits each year, according to its website. It operates the state's only Level 1 trauma center.

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Yu reported from Phoenix.