Residents who had stayed up for Sehri (pre-dawn meal) saw the inferno break out just before 1 a.m.
After sensing the smoke smell about an hour after midnight Tuesday, the fasting Muslims came out of their homes and began running around, frantically knocking on neighbours' doors to wake them up, the Daily Mail reported on Thursday.
Khalid Suleman Ahmed, who lived on the eighth floor of Grenfell Tower, said: "No fire alarms went off and there were no warning. I was playing PlayStation waiting to eat suhuur when I smelt smoke.
"I got up and looked out of my window and saw the seventh floor smoking. I woke my auntie up, then got clothes on and started knocking on neighbours' doors."
Rashida, a resident, told Sky News how fasting Muslims may have saved lives in the tower block as many of them were awake.
"So most of the families around here would have been awake," she said.
Nadia Yousuf, 29, also said that Muslim residents were among the first to alert neighbours to the blaze as they woke up to prepare to break their fast.
A number of Islamic cultural centres and mosques like the Al-Manaar Mosque opened their doors to help those affected.
The nearby St. Clement's and St. James' church and local Sikh temples also opened their doors to people who were evacuated.
A woman near the scene told reporters: "If it wasn't for all these young Muslim boys around here helping us coming from the mosque, a lot more people would have been dead.
"They were the first people with bags of water giving to people and helping, running and telling people."
Andre Barroso, 33, told The Independent: "Muslims played a big part in getting a lot of people out. Most of the people I could see were Muslim. They have also been providing food and clothes."
Twenty people are fighting for their lives in a critical condition with 78 people taken to six different hospitals across London.