Obama Calls For 'Prayer and Reflection' After Colo. Massacre

President Barack Obama called on the nation to turn to "prayer and reflection" following the mass shooting at a Colorado movie theater that left 12 people dead, and vowed the federal government will do "everything necessary" to bring to justice those responsible.

“We may never understand what leads anyone to terrorize their fellow human beings.  Such evil is senseless – beyond reason,” Obama said in his weekly address, one day after the shooting. “While we will never know fully what causes someone to take the life of another, we do know what makes that life worth living."

Obama said the shooting is a reminder that "our time here is limited and it is precious," echoing his first remarks about it on Friday.

“This weekend I hope everyone takes some time for prayer and reflection – for the victims of this terrible tragedy, for the people who knew them and loved them, for those who are still struggling to recover, and for all the victims of the less publicized acts of violence that plague our communities on a daily basis,” Obama said.

Obama and Republican rival Mitt Romney have both asked Colorado television stations to temporarily pull their attack ads against one another in the wake of the shooting.