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.