There are more than ten fires a week in London's care homes and sheltered accommodation, London Fire Brigade (LFB) has revealed.
Last year there were 540 fires in such homes - with two people killed and 26 injured as a result.
The LFB says reducing the number is a top priority and warned too many homes are not being fitted with sprinklers.
The brigade said the vast majority of care homes in the capital do not have the devices.
Deputy Commissioner Rita Dexter said: "Older people, people with mental health problems and those with mobility issues are the group most at risk from fire.
"We are concerned by the number of vulnerable people like this who are still harmed or killed by fire in places where they should be safe.
"That's why we want to see all residential care homes fitted with sprinklers."
The latest figures from the Care Quality Commission show there are about 900 care homes for older people and other vulnerable groups in London.
In 2011 BBC London revealed how dozens of care homes were ordered to improve after failing to achieve even basic fire safety standards.