The fourth floor and attic roof at trendy Bow Wharf have been incinerated as the fire raged through the five-storey block today.
The cause of the fire is still unknown at this stage, yet a picture shows solar panels on fire at the waterside development, where homes are on sale for more than £1million.
One shocked witness told the MailOnline: "I noticed massive billows of smoke when I was leaving my flat so I quickly rushed back and noticed it was the building opposite.
"The spread seemed concentrated around the solar panels on the top. It looked a bit like the solar panels were on fire."
At least 75% of the roof has been destroyed, while eighty fire fighters desperately try to dampen the blaze.
Mile End park and a number of roads surrounding the development in Mace Street had to be evacuated after the fire broke out at around 11am this morning.
A witness at the scene said there were "clearly access issues" for emergency crews trying to reach the blaze.
Twitter user marny wrote: "Command Unit in place but clearly access issues - had been brought up during planning stage for this new build.
"Ladder in place finally, clearly serious access issues to the building site, all highlighted by residents earlier."
As crews appeared to begin to bring the blaze under control at about 12.50pm, marny wrote: "Incident closing - heavy smoke movement due to east wind, Bow Wharf evacuated, Grove Road closed."
The last five units - ranging between £999,950 and £1,025,000 - were recently launched to buyers.
The entire development comprises of 24 units in total, including 5 houses and 19 apartments all of which will be finished to a high standard throughout. Ten of the homes will be affordable.
Construction and development firm Rooff Limited and H20Urban are joint venture partners and contractors on the half acre site at the junction of the Regents and Hereford Union canals.
Works started late 2015 and were due to be completed this summer.
A London Fire Brigade spokesman said: "Twelve fire engines and around 80 firefighters and officers have been called to a fire at a building under construction on Bow Wharf, Wennington Road E3.
"The fourth floor and roof of the five storey residential block are alight.
"The Brigade was called at 1110. Crews from Bethnal Green, Homerton, Shadwell, Shoreditch, Whitechapel, Poplar, Millwall and other surrounding fire stations are at the scene.
"The cause of the fire is not known at this stage."
H20Urban has been contacted for comment.
The cause of the fire is under investigation.
From Mirror - Rachel Bishop..