Dozens of patients were evacuated from the hospital in North London after part of the building was completely burned.
London fire brigade said that 45 people had been rescued from the wards in the hospital Chase Farm near Enfield, seven people received intensive treatment from exposure to toxic smoke at the scene.
Fifteen people moved to neighboring areas as a result of the fire, which was attended by 58 firefighters and 8 fire engines.
They arrived at the scene at 10:10 PM on Sunday. A large part of the two-storey building was on fire.
The cause of the fire remains unknown.
Firefighters managed to extinguish the fire after 3 hours.
Hospital Chase Farm is part of the Foundation of the Royal Free London NHS Foundation Trust.