The woman managed to use her cellphone or hand-held device to send the text message, which was received by the Foreign Affairs Department in Ottawa, nearly 3,000 km (1,900 miles) away. It was relayed to Canadian diplomats back in Haiti, who rushed to provide assistance.
Foreign Minister Lawrence Cannon's office later said it understood she was safe but declined to provide details.
Officials were still searching for two of the 82 Canadian police officers who are part of a U.N. force in the impoverished country, including the acting police commissioner for the force, Supt. Doug Coates. His office was in the U.N. building that collapsed.
Canada's Haitian-born governor general, Michaelle Jean, broke down in tears as she reflected on the devastation to her native country.
Jean is the representative of Queen Elizabeth, Canada's head of state, and said the situation in Haiti had monopolized her attention since the earthquake struck on Tuesday.
The images and news reports are unbearable to watch -- so much distress, suffering and loss, she told reporters after attending a briefing session with Prime Minister Stephen Harper.
Harper and Jean were told the Canadian Forces were in the process of arranging for ships, helicopters and relief equipment to be sent to Haiti.
A 20-strong military reconnaissance team was already flying in on Wednesday and the military's Disaster Assistance Response Team was being readied to be sent as soon as the advance group says exactly what is needed.
Transport aircraft will fly in three rescue helicopters on Thursday. The destroyer HMCS Athabaskan and the frigate HMCS Halifax and 500 service personnel will also depart Nova Scotia on Thursday with another helicopter, with the emphasis on providing light engineering and medical help.
Canada has a large Haitian population, and Haiti is the largest recipient in the Americas of Canadian aid. Ottawa has allocated an initial C$5 million ($4.9 million) for emergency relief.
(Editing by Rob Wilson)