Ten fire engines are fighting the flames raging through an office block in Hackney.
A spokeswoman for the London Fire Brigade said that firefighters are concerned about gas cylinders close by to the fire.
“We were just leaving and there was some light smoke coming out, and then it became really intense really quickly,” says Rukaya Ceser, a nearby witness.
“I heard sirens coming down the street almost immediately and there are about five fire engines here, as well as police.
“They have closed off the area and are trying to keep people away from the fire.
“There is a garage and it is next to a church so I am not sure whether the fire has spread to both.”
Fire teams aren’t sure if there is anyone left in the building.
According to the Greater Anglia Twitter account, all lines are blocked at London Fields station due to the fire.