A Toronto ambulance dispatch centre says 12 staff members have tested positive for COVID-19.
A spokesperson for Toronto Paramedic Services says nine of the infected people were still in quarantine as of Wednesday morning.
Three people who contracted the illness had already returned to work at the Central Ambulance Communications Centre.
Eighteen others were in self-isolation due to the outbreak.
Approximately 130 people work at the call centre as emergency medical dispatchers and call takers.
A statement from the centre says the outbreak hasn’t disrupted ambulance delivery.