Toronto Fire officials spoke out after the Grenfell Tower inferno to assure residents that protections in the Ontario Building Code and routine fire safety inspections will prevent a similar incident here.
The toll had previously been put at 30.
Ms May, who has since ordered more boots on the ground at the scene, is said to have "welled up" after hearing harrowing accounts from people caught up in the fire.
Reports suggest that a renovation project on Grenfell Tower a year ago intentionally did not include safety devices such as sprinklers and doors created to keep the fire from spreading. For police, fire and emergency crews inside the tower, "it is incredibly emotional working in there", Cundy said.
"I believe there may be people who were in Grenfell Tower that people may not know were missing and may not have realised they were in there on the night. There is also a real possibility that there may be people in the building that no one knows are missing", he added.
This will ensure those involved in the response to the tragedy are able "to receive targeted support should they need it", Downing Street said.
Earlier the group, made up of survivors of the fire, evacuees from nearby buildings, volunteers and community leaders, criticised Kensington and Chelsea Tenant Management Organisation for its reaction to the disaster.
He warned that a full forensic and systematic search will take weeks to complete, adding: "We must also prepare people for the awful reality that some people may not be identified due to the intensity of the fire".
In a statement to the Press Association, they said: "With the exception of very few junior officers, the estate managers have been invisible in the aftermath of the tragedy".
The investigation into the fire will span a "wide range of areas", Cundy said, from its original construction, to the refurbishment and how it has been managed and maintained.
Speaking after attending a local church service in memory of the victims, he said the fire was "a national disaster that requires a national response".
But Mark Cripps, a spokesman for Municipal Affairs Minister Bill Mauro, said the Ontario Building Code also stipulates that if "combustible cladding" is used on a building over three storeys, the structure must be equipped with automatic sprinkler protection.
Conditions in the staircase were so cramped that fire crews were told they could stay outside to help or go into the burning building without their full breathing apparatus and just their eye gear.
Later on Sunday, former United Kingdom chancellor Philip Hammond said the cladding material used on the building was banned on British high-rises.
Meanwhile, Prime Minister Theresa May has been criticized for her slowness in visiting the victims of the fire - her visits took place more than 48 hours after the fire broke out - and refusal to answer questions about government oversights that might have increased the deadly nature of the blaze.
UK Chancellor Philip Hammond today indicated that flammable material suspected to have been used was most likely banned in the UK.