About 100 firefighters set fireplace to a block of flats in Battersi, Southwest London.
The London Brigade (LFB) said that an “significant volume and roof of the five -storey residential building on Mesaul Road was destroyed.
19:00 The fire crew was collected immediately after BST and brought the fire under control at 23:01.
Around 150 people were wearing a breathing equipment by the fire fighting crew, while the firefighters used a large turnteable ladder to help deal with flames from above as a water tower.
Three people were treated by paramedics at the scene.
The London Ambulance Service (LAS) said it was called to the block near the Junction of Hope Street and Benhem Close shortly before 19:30 BST.
A Las spokesperson said and the ambulance crew, an incident reaction officer and its dangerous area reaction team members participated in the fire.
The explanation for the fireplace will likely be investigated.
With inputs from BBC