London Fire Brigade Commissioner Dany Cotton has said she can't be sure a disaster like the Grenfell Tower blaze "wouldn't happen again".
The fire chief told Sky News the building "should never have behaved like that in a fire situation", adding: "I would never be able to say it won't happen again, I just hope and pray it never does".
She went on to say: "I'm staggered we don't have sprinklers in domestic premises and schools. They save lives. They keep people safe, as well as putting the fire out."
Six months after the fire that killed 71 people, including an unborn baby, a public inquiry has now begun with a preliminary hearing providing information about the time frame and structure of the investigation.
So far only 42 of the 208 families whose homes were destroyed in the blaze have been rehomed permanently, with many facing Christmas in hotels.
Ms Cotton said the inquiry "needs to explore every single aspect of what happened on that tragic night and beforehand".
Describing her arrival at the scene of the fire, she added: "I was just incredulous. It genuinely looked like something that couldn't happen in England in this day and age."
Part of the inquiry will look at equipment used on the night of the fire and the "stay put policy" which advised residents to stay inside until the fire was contained in its unit of origin.
Praising her staff who went back into the burning block time and time again, Ms Cotton said she would be "fiercely defensive of the firefighters" and wouldn't want to see any individuals singled out.
Many firefighters who worked during the night of the Grenfell disaster are still receiving counselling to help them recover from the trauma of the fire.
No evidence was heard during the two-day hearing which marks the beginning of the inquiry, however during representations concerns were raised that survivors wouldn't be listened to.
Core participant status has been granted to 424 individuals and groups, allowing them the right to access evidence and challenge inquiry witnesses.
The Equality and Human Rights Commission (EHRC) has now also launched an inquiry into the fire, part of which will look at whether authorities failed in their duty to protect life.
Metropolitan Police is also investigating offences including manslaughter, corporate manslaughter, misconduct in public office and breaches of fire safety regulations in relation to the fire.
Bereaved families and survivors of the fire have presented a petition to Downing Street, calling on Theresa May to appoint an independent panel to sit alongside the judge and be able to observe the decisions he makes.
Former resident Nicholas Burton presented the petition, which attracted over 16,000 signatures, including those of singer Adele and actor Noel Clarke, to staff at Number 10.
The interim report into the fire is not expected to be published until next autumn.