By Bradley Jolly More than 125 firefighters are tackling a blaze at a block of flats tonight in northwest London. Twenty fire engines dashed to the fire in Wembley, believed to have started in the building’s roof or one of the upper floors. The block and surrounding buildings have been evacuated as a precautionary measure, London Fire Brigade says. A statement said: “People are advised to avoid the area as crews respond. One of the Brigade’s 32 metre turntable ladders is being used as a water tower to help extinguish the fire. “Control Officers have taken eight calls reporting the fire, with t…