Photographs have been released by a family friend of two victims of the fatal house fire in Leicester.
The boys have been named locally as 15-year-old Jamal Taufiq and 17-year-old Bilal.
Their mother Shehnila and 19-year-old sister Zainab also died in the fire.
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The Ukip leader confirmed he had "no prior warning" of Douglas Carswell's resignation from the party as he hit out at the "staunch Tory".
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.
The violence began after a counter-protester allegedly doused a female rally organiser with pepper spray.