Four and a half years ago, the sound of horns and alarms did not have the same effect on Jerzy Nowak.
On the morning of April 16, 2007, the Virginia Tech horticulture professor was at his desk in Sanders Hall, writing research grant proposals, when the wail of sirens split the crisp, snowy air. It would be hours before he learned that a gunman was loose on campus -- and more than half a day would pass before university officials arrived at his home to confirm that his wife, French professor Jocelyne Couture-Nowak, was among the 32 slain.
So when the alarms again sounded Thursday morning, Nowak was immobilized.
"I froze ... like my life just stopped for a split second," he said in his thick Polish accent. "I actually reacted ... much stronger than last time. Because, last time, I was not aware what was going on."