Emergency services have been called back to Canberra Hospital after another incident, although no evacuations have been required this time.
Earlier this week, 60 patients were evacuated and surgeries were cancelled after a fire at the hospital's electrical switchroom on Wednesday night.
Firefighters were called back to the hospital on Sunday morning for an unrelated incident.
"A power supply room has been isolated following a smell of gas being detected in the area," the Emergency Services Agency said in a statement.
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"No patients or staff have been evacuated."
Firefighters responded after a Triple Zero call about 7.10am, but were scaling back their work by 9.20am.
"Electricians are now identifying damage to the power supply room. No evacuations were necessary and no injuries have been reported," the agency said.