Abu Musab al-Zarqawi exleader of Al Qaeda in Iraq , made the same mistake in bombing a wedding, causing carnage, death and injuries, which led to the killing of 60 in Amman Jordan in 2005. He found this vile act, had unexpected consequences and backlash with loss of support for his vile group by everyone, including Al Qaeda leadership and sponsers , he ended up having to apologize making a excuse saying it wasn't the intended target , but plenty damage done.
Daesh haven't obviously learned this lesson , causing this vile horror , at this wedding , I hope it will be just as detrimental or worse for them worldwide.
It seems to be a vile act by a failing group, now desperate to stay relative , and to shore up its dwindling support , and its continuing loss of 45% of thier territory, which is thankfully being liberated by the allies.
With more Daesh failures, defeats and losses, the more desparate these Nazis will become, to keep thier brand known. Which unfortunately will result in more of these vile attacks around the world.
My sympathies go out to the families and friends, and RIP to the victims of this unjustified sick act . I hope the backlash and revenge is swift and hard.