The fire spread from the ground floor to the sixth floor at De Pass Gardens, forcing people to evacuate the building and nearby apartments.
A man and woman were treated for smoke inhalation but nobody else appeared to be hurt, Sky News reported. The cause of the fire was not immediately known.
“Any residents who are affected by the fire are advised to go to the rest centre at Thames View Community Centre on Bastable Road," the London Fire Brigade said. "Transport is available from De Pass Gardens to take people there.”
When firefighters finally extinguished the flames, some 20 flats were destroyed and another 10 suffered damage, the BBC reported. Videos and pictures posted on Twitter showed extensive damage.
Firefighters were called from the Barking, Dagenham, East Ham and surrounding fire stations.
“Crews worked really hard to put the fire out," Station Manager Andy Maloney said.
Around 1:30 p.m. ET, the London Fire Brigade announced the fire was under control.
Mihaela Gheorghe, who lived in the building, said she'd worried a fire was bound to happen and had raised several safety questions about the wooden balconies in the East London flats, the BBC reported.
"I was in my fourth-floor flat when the fire started. We ran out. The fire brigade came but they found it hard to find a water supply at first," Gheorghe said. "We raised several issues to the builder, the maintenance companies and the council about the safety of having all these wooden balconies."
It was not clear whether the wooden balconies had contributed to the blaze.