Police and fire services attempted to evacuate the concrete block and said "a number of people are being treated for a range of injuries", including at least two for smoke inhalation.
The government said that there was "no specific reason for consumers to switch off their fridge freezer pending further investigation".
Ms McCormack said the tests carried out as part of the investigation were "small scale", but added: "All I can say at the moment is they (tiles and insulation) don't pass any safety tests".
In its most detailed briefing yet on the criminal investigation, the Metropolitan Police on Friday confirmed residents' suspicions that the June 14 inferno at Grenfell Tower was touched off by a refrigerator fire.
Downing Street revealed on Monday that 600 high-rise tower blocks in the United Kingdom could have similarly unsafe cladding, though only three were identified as "combustible".
She said: "We are looking at every criminal offence from manslaughter onwards".
According to emerging reports, police in London are considering manslaughter charges in the aftermath of the Grenfell Tower tragedy.
"What we are being told at the moment by the Building Research Establishment is that the cladding and insulation failed all safety tests".
London police ponder manslaughter in tower fire
McCormack said that every intact body has been removed from the building and that nine of the dead have been formally identified. One tribute, from a firefighter from a station in the Kensington and Chelsea borough read: "20th floor, we tried. we're sorry".
'Preliminary tests on the insultation samples collected from Grenfell Tower show that they combusted soon after the test started, ' she said.
She appealed for people to come forward with information about anyone who may have been in the building on the night of the fire.
The affected buildings, housing potentially thousands of residents, are in eight local authority areas, including Manchester, Plymouth and Camden in north London, Communities and Local Government Secretary Sajid Javid said in a letter to lawmakers. That comes after London Mayor Sadiq Khan pledged to seek an amnesty for people who may have been living in the public housing block illegally.
Fears about cladding is not limited to apartment buildings, and at least one hotel chain is calling in experts to make certain it meets safety regulations. Premier Inn said Friday it had "concerns" about the material used on some of its buildings, though it is different from the type used at Grenfell Tower.
"The Home Office has assured us that they are not interested in people's immigration status and we are not interested in looking at that", McCormack said. I remain really concerned though that we do not have a complete picture.
"What we are interested in is making sure that we know who is missing and we take every possible step to establish if they are safe and well".
Hundreds of people may have to be evacuated from tower blocks across the country, in what could be one of Britain's largest peacetime evacuations.
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