A 22-year-old man has been arrested in relation to the murder of Richard Bowes who died after being attacked in Ealing during riots this week's London riots.
Mr Bowes, 68, was attacked as he tried to stamp out a fire in the suburb and suffered serious head injuries as a result. He died just before midnight last night, Scotland Yard said.
His next of kin have been informed and a post mortem examination will be held soon.
Detective Chief Inspector John McFarlane, of the Met's Homicide and Serious Crime Command, told Sky News: "This was a brutal incident that resulted in the senseless killing of an innocent man.
"I still need the assistance of the community who may have witnessed the attack to come forward and provide information or images they may have recorded on mobile devices.
"This information could be crucial in catching his killer."
Scotland Yard said officers were in the area dealing with violent disorder when they became aware of Mr Bowes being attacked.
They managed to reach him to administer first aid despite missiles being rained at them, the Met added.