The fire service is at the scene of an incident at the Mater Hospital in North Belfast.
A witness described seeing smoke from the building and the PSNI is also at the scene.
Belfast Trust said: "The fire service are attending an incident at the Mater."
Belfast fire crews battle blazes across in city
Councillor Julie-Anne Corr-Johnston said: "Fire Brigade and PSNI at the Mater .. not sure what’s happened but please avoid the area and allow the emergency services to do their job."
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