April 20 - a day of mourning

The governor of Virginia has declared April 20, 2007, a day of mourning for the Virginia Tech students and teachers killed in Monday's massacre.

Vigils and prayer services are being held from coast to coast.

Here's ABC's Eric Horng in Blacksbug, Virginia.

As this week of shock and sorrow draws to a close, memorials to the victims grow larger.

"To know that something like this could happen to such good people, I mean it hurts," said Sierra McKeon, Virginia Tech student.

Many have spent the past four days grieving and the past four nights in fear.

"Just having dreams that people that I'm with and I are being shot at, just things like that. Half the time I don't even remember them, just wake up feeling upset," said Sara Defluri, classmate of gunman.

Late yesterday, two more wounded students left the hospital. Those who remain were treated to an impromptu concert by the marching band. Classes are scheduled to resume April 23 but the university expects many to call it a year.

"We are going to encourage them very strongly to continue in their classes, but also to do it in the context of what they're capable of handling under the current circumstances," said Mark McNamee, VA Tech provost.

And the struggle for answers continues - how a young man went from misfit to mass murderer with hardly anyone acting on the alarm bells. A court-ordered mental health evaluation of Seung Hui Cho found him "mentally ill and in need of hospitalization" and "an imminent danger," but there were no red flags at the gun counter.

A state police background check was ran, and it came back clean. Clean because Cho was ordered to undergo outpatient care, rather than inpatient.

Threats have been made against Cho's relatives, who live in suburban Washington. The South Korean Embassy said U.S. law enforcement officials are moving the couple from place to place to ensure their safety.