The director of clinical and medical affairs, Frederic Abergel, said the agency is asking hospitals to reschedule non-urgent surgeries to free up medical professionals to help their colleagues in emergency rooms.
Officials at Sacré-Coeur Hospital told the CBC that Thursday morning there were 71 patients in the hospital's emergency room, which only accommodates 46.
The director of professional services at the hospital, Dr. Josée Savoie, said there were also patients waiting in a separate overflow room.
She said many patients arrived suffering from the flu and gastro-intestinal viruses.
"But there are many other reasons and we're not able to tell you right now exactly what the reasons are," she said.
The Montreal General Hospital said it's operating at 200 per cent capacity. St. Mary's Hospital is operating at 227 per cent.