(Recasts, updates with statement from shooter's family)

By Andrea Hopkins

BLACKSBURG, Va., April 20 (Reuters) - The family of the Virginia Tech shooter issued a heartbroken apology on Friday for his "unspeakable actions" as the campus emptied and memorial services began for some of the 32 victims of Monday's massacre.

"We feel hopeless, helpless and lost," the family, which remained in seclusion, said in a statement that referred to the shooter as Seung-Hui Cho. "He has made the world weep. We are living a nightmare.

"No words can express our sadness that 32 innocent people lost their lives this week in such a terrible, senseless tragedy. We are heartbroken," the statement read as the country marked a day of mourning for the victims of the worst mass shooting in modern U.S. history.

Thousands of grieving students headed home to family as a tragic week drew to a close, and mourning shifted to hometowns across the United States and around the world with the first funerals for students and teachers killed in the rampage.

A few blocks from campus, Blacksburg Presbyterian Church filled to overflowing for the service for Kevin Granata, one of four teachers killed on Monday by the gunman, identified by police and university officials as Cho Seung-Hui.

"It was a tough one. Very tough, very tough. Unimaginable," the Rev. Alex Evans said of the service as mourners wearing the orange and maroon of Virginia Tech poured out of the stone church, many still wiping away tears.

Granata, a biomechanics professor, lacrosse coach and father of three, was killed when he ran into the hallway to help students when the shooting began.

Moments of silence were observed on Friday on the trading floors of financial markets in New York and Chicago and church bells rang out from coast to coast to mark the tragedy.

Cho, 23, a mentally disturbed English major, killed himself before police could intervene in the shooting spree on this sprawling campus in the mountains of southwest Virginia.

Four days after the attack, and on the eighth anniversary of the shooting at Columbine High School in Colorado in which 15 people died, a heightened sense of alert gripped the United States, especially at educational institutions.

Security alerts involving guns, bombs and suspects with explosives forced the evacuation on Friday of schools in Colorado and California, the Arizona state Capitol and a NASA building in Houston where a gunman killed a hostage and then himself.

EXHAUSTED GRIEF

After days of round-the-clock tears and vigils at Virginia Tech, only a small crowd of mourners gathered to observe a moment of silence at a makeshift memorial on the grounds of the university, home to some 25,000 full-time students.

More funerals and memorial services were scheduled on Saturday near Blacksburg, while other tributes were taking place overseas for victims from India, Israel and Peru.

The campus newspaper was closed and dark, planning no more stories on the shooting until a special edition on Monday, when classes are scheduled to resume.

Editor Amie Steele, 21, said the surreal chaos that gripped student journalists as they struggled to cover the biggest story of their lives had been replaced by exhausted grief.

"We all need a break, to calm down and regroup for Monday when students will finally be back in town," Steele said.

The campus bookstore was a rare spot of activity on campus, as visiting parents, families and journalists lined up to buy Virginia Tech T-shirts and sweaters to honor an alumni request that people nationwide wear the school's orange and maroon.

"The last few days have been crazy," said bookstore clerk Pierson Booher, an architecture student. "We got 1,600 mail orders yesterday morning alone."

President George W. Bush wore an orange and maroon tie on Friday, lawmakers on Capitol Hill sported maroon-and-orange lapel ribbons, Pentagon staff donned the school colors, and national news anchors wore orange ties or jackets. Athletes and students across the country honored the day of mourning.

Students and parents at Virginia Tech said they were touched by the outpouring of support.

"I think it's nice. It shows their dedication and spirit. But we have to keep moving on," said Dave Nazaruk, on campus with his son Aaron, 18, a high school student who will attend Virginia Tech in the fall.

The investigation into Cho's rampage continued. Police revealed on Wednesday the gunman had a history of mental illness and had been investigated for suspected stalking incidents in 2005. Cho's parents and sister, who live in a Virginia suburb of Washington, are under police protection.

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