London Fire Brigade's commissioner is to step down four months early in the wake of criticism over the service's response to the Grenfell fire.
Dany Cotton, 50, previously announced she was standing down from the London Fire Brigade (LFB) in April 2020.
She was facing calls to resign after a critical public inquiry report into the Grenfell Tower fire which killed 72 people in June 2017.
Grenfell United said the change in leadership would "keep Londoners safe".
The statement on behalf of survivors and bereaved families of the fire, added: "Sir Martin Moore-Bick raised serious concerns that the London Fire Brigade was an institution at risk of not learning the lessons of Grenfell.
"The phase one report has important recommendations for the LFB. The incoming commissioner must ensure that they move swiftly to ensure those recommendations are implemented.
"The LFB leadership must be determined in their efforts to ensure the lessons of Grenfell are learnt."
Ms Cotton, who will leave her role at the end of December, said Grenfell Tower was "without doubt the worst fire" that LFB had ever faced.
An inquiry into the Grenfell fire, which examined what happened on the night of 14 June 2017, concluded that "many more lives" could have been saved if the advice to residents to "stay put" had been abandoned earlier than 02:35 BST.
It said LFB's preparations for such a fire were "gravely inadequate".
Survivors called for senior fire brigade staff to be sacked and prosecuted, saying that the brigade is "in the hands of people that are incapable of their jobs".
Nabil Choucair, who lost six family members in the Grenfell Tower fire, said it was a "disgrace" it had taken this long for Ms Cotton to step down.
"It's a shame that it's taken pressure from the families," he added.
"If she cared and understood, she would have done it a long time ago. It should not have taken this long, it's a disgrace."
Ms Cotton said she had worked on "some of the most painful incidents to have occurred in LFB's history" during her 32 years with the service.
Three months into the job, she attended the Clapham Junction rail disaster where 33 people died.
She also led crews when tackling the fire which ravaged the Cutty Sark in 2007.
By BBC London's political correspondent Karl Mercer
There was a sense of inevitability about the decision of Dany Cotton to stand down early.
In his report, retired judge Sir Martin Moore-Bick recalled her evidence to the inquiry - in which she said she wouldn't have done anything different on the night of the Grenfell fire - branding her remarks "remarkably insensitive".
Her words had infuriated the Grenfell families who called for Ms Cotton to go and now she has, after a month of "discussions" with the mayor.
He clearly believes she is no longer the person to see the brigade through the changes it needs to make, despite appointing her as London's first female fire commissioner at the start of 2017.
The Mayor of London Sadiq Khan praised Ms Cotton for more than three decades with the fire brigade but added that her decision to go was "the right one".
He said he would be appointing a new fire commissioner shortly and added that they will "quickly take on the responsibility" of delivering the Grenfell Tower Inquiry report recommendations.