Those who LEGITIMATELY mourn an unnecessary death have nothing to gain by setting fires or smashing windows or looting or smashing anything.
Another element showed up to POUNCE on the opportunity. Is it a planned mob with instructions of what to do or are they just individual opportunists there to see what they can steal for themselves under the guise of emotional pain? I don't know. Do you?
They just want an excuse to be a-holes. How does killing others morn one dead person? How does wanton destruction solve anything? All this assoholic behavior besmirches the name and reputation of the person they are “supposedly” grieving (not that they really know or even care about them).