Four people are believed to be injured after a crane collapsed on a house in Bow, east London.
London Fire Brigade tweeted: "A 20 meter crane has collapsed onto a terraced house in #Bow. Fire crews are working to free people trapped inside. Please avoid the area."
It is not clear yet whether those people have been rescued.
Police said they had received reports that four people were injured and the Ambulance Service said a number of crews and "specialist resources" were at the scene.
Bridget Teirney tweeted: "Crane behind my building just collapsed in Bow, London. At least one man crushed, crane went through 2 house."