What does one say?

What does one say to the horrible events in Lancaster, PA? I have no words. I think that one can only hold before God in prayer the mourning parents, family and community.

Psalm 13 (NRSV)

How long, O Lord? Will you forget me forever? How long will you hide your face from me? How long must I bear pain in my soul, and have sorrow in my heart all day long? How long shall my enemy be exalted over me? Consider and answer me, O Lord my God! Give light to my eyes, or I will sleep the sleep of death, and my enemy will say, "I have prevailed"; my foes will rejoice because I am shaken. But I trusted in your steadfast love; my heart shall rejoice in your salvation. I will sing to the Lord, because he has dealt bountifully with me.