LONDON, March 23 - Britain's domestic intelligence service said its operational response was fully mobilized in support of the police after an attack in London on Wednesday that killed four people. 'We stand shoulder-to-shoulder with our police colleagues, grieving at their loss while also applauding the professional excellence of their response,' MI5 Director General Andrew Parker said in a statement. London police said earlier on Thursday they had arrested eight people in connection with the investigation.
