The school sent out an e-mail about the shootings about two hours later, but by that time student gunman Seung-Hui Cho, 23, had chained the doors of a classroom building and killed 30 other students and faculty before taking his life.
Virginia Tech has responded to the government's findings, saying it believes its officials acted appropriately on that day.
Though school officials won't face criminal charges for breaking the law, the university could be fined as much as $55,000.
The Associated Press contributed to this report.
