Eleven people managed to escape from their burning house before fire tore through it in the early hours of yesterday morning.
The occupants, all believed to be related and from Hungary, fled the blaze in the two-storey property in Susannah Street, Poplar.
Fire spread through most of the ground floor and part of the first floor but no-one was injured.
A discarded cigarette is thought to be the cause of the fire.
Four engines and around twenty fire fighters were called to the scene at 3.25am but the family had left before they arrived.
It took the crews just over an hour to control the blaze.
Fire fighters do not believe there was a smoke alarm in the property.
Borough Commander for Tower Hamlets, Bruce Epsly said: “I cannot stress enough how important it is to make sure that your cigarettes and matches are completely out once you’ve finished with them.
“Fortunately, no one was seriously hurt this time but we do get fires every year where people are injured, or even worse, by fires caused by cigarettes.”
He also used the accident as an example of the importance of getting a smoke alarm fitted.
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