What else can be expected from those who are treated like pariahs in their own country by the majority population, these people face legal and social discrimination on the daily basis.
They were forced to take law in their own hands because their loved ones are being exploded constantly into smithereens before their own eyes, and the perpetrators are hardly ever caught and brought to justice.
The human patience is not infinite, they were running out of their patience and had to register their protest. Whether one agrees or disagrees the way they reacted; but this is the way the hapless, helpless and desperate people react.