Many were moved to tears after a moment of silent contemplation outside the Notting Hill Methodist Church.
The Rev Mike Long invited those present to light candles to place on the steps of the church on Wednesday evening (June 14).
He then played Amazing Grace on his flute as members of the crowd sang along.
He said: "There are times when all the words we can say are not adequate and sometimes words fail us because no words can do justice to how we feel, or what we have seen or what has happened.
"Today is one of those days.
"What we can simply do is look to all that we have seen today which is good, which is fabulous - people getting together."
"Let light triumph over all that is rotten, that is desperate and that defies our understanding."
It came after the Prime Minister promised a "proper investigation."
Theresa May paid tribute to the efforts of the emergency services and said support should be given to the hundreds affected by the fire.
Speaking from Downing Street she said: "There are people tonight who have no home to go to, they have lost absolutely everything, so our focus must be on support to them.
"In due course, when the scene is secure, when it's possible to identify the cause of this fire, then of course there will be proper investigation and if there are any lessons to be learnt they will be, and action will be taken."
The Metropolitan Police Casualty Bureau is open for members of the public who are concerned about relatives or friends who may have been affected the fire.
The number for the Casualty Bureau is 0800 0961 233.
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