Perhaps in the scheme of things as far as military operations are concerned this is "low" collateral damage. But if 3000+ people were wounded that means potentially tens of thousands experienced the traumatic event of explosives going off in a public space. And hundreds more are mourning family.

Negative. Anyone can use a pager or a walkie talkie. If this were to have happened in say the US, it would 100% be considered not only terrorism, but an act of war.