Columbine Shootings 10 Years Later: Students, Teacher Still Haunted by Post-Traumatic Stress

April 13, 2009— -- First in a series on the Columbine shootings, 10 years later.

"I knew he was going to die," said Friesen, who has had to unearththe trauma again as the victims, the country -- and the media -- bracefor the 10th anniversary of the most iconic of allschool shootings.

"There were relatively few who were right at the heart of [theshootings] and were direct post-traumatic stress syndrome candidates,"Ochberg told ABCNews.com. "But there were relatively many for whomColumbine was their Gettysburg."

"It changed them, and if they were young, they grew up fast," he said. "Within that group, some are better and some are worse."

Friesen had been holed down in his classroom for three hours that day,with the incessant blaring of the school alarms, exploding pipe bombsand students' screams.

"A gun and holster is the worst one for me," said the 58-year-old, whohas retired from teaching and lives in Littleton. "But you live withit. You learn to cope."