Flowers are seen at the entrance to the Royal Artillery Barracks in Woolwich in southeast London, May 23, 2013. A serving soldier was hacked to death by two attackers wielding knives including a meat cleaver near the Royal Artillery Barracks in Woolwich on Wednesday afternoon. (Xinhua/Bimal Gautam)

Flowers are laid at the entrance to the Royal Artillery Barracks in Woolwich in southeast London, May 23, 2013. A serving soldier was hacked to death by two attackers wielding knives including a meat cleaver near the Royal Artillery Barracks in Woolwich on Wednesday afternoon. (Xinhua/Bimal Gautam)

Flowers are seen at the entrance to the Royal Artillery Barracks in Woolwich in southeast London, May 23, 2013. A serving soldier was hacked to death by two attackers wielding knives including a meat cleaver near the Royal Artillery Barracks in Woolwich on Wednesday afternoon. (Xinhua/Bimal Gautam)

Flowers are laid at the entrance to the Royal Artillery Barracks as two soldiers pass by in Woolwich in southeast London, May 23, 2013. A serving soldier was hacked to death by two attackers wielding knives including a meat cleaver near the Royal Artillery Barracks in Woolwich on Wednesday afternoon. (Xinhua/Bimal Gautam)

London Mayor Boris Johnson (L front) inspects the neighbourhood near the Royal Artillery Barracks in Woolwich in southeast London, May 23, 2013. A serving soldier was hacked to death by two attackers wielding knives including a meat cleaver near the Royal Artillery Barracks in Woolwich on Wednesday afternoon. (Xinhua/Bimal Gautam)