Virginia Tech on lockdown

Virginia Tech was locked down Thursday morning after witnesses reported seeing a man carrying what may have been a gun on campus. Three children attending a summer camp told police they saw a man walking quickly by the campus volleyball courts, armed with what looked like a handgun covered by a cloth. The university released an alert at 9:37 a.m. and the campus went into lockdown.

Virginia Tech Police released a sketch of the person believed to be carrying the weapon and posted it on its website at 12:44 p.m. As of 1 p.m., police were still combing the campus. Classes have been cancelled for the remainder of the day and the school continues to update its website and Twitter account with new details. Students have also been alerted to the situation via text messages and emails.

Virginia Tech was the site of a 2007 massacre that left 33 people dead. Federal authorities ruled that the school acted too slowly in alerting its students and staff to the threat, sending out an email more than two hours after gunman Seung-Hui Cho had already shot two students. The university upgraded its emergency alert system after the shooting.

Officials Thursday morning said they were looking for a 6-foot-tall white man with light brown hair and a blue and white striped shirt. The children who gave the initial report were interviewed by police and their claims were deemed to be credible.

Update: Viginia Tech officials lifted the lockdown around 2:45 p.m. The alleged gunman was not found.