Reports of armed man shut down Virginia Tech campus.
A report of a man with a gun led to a lockdown and intense building-to-building search at Virginia Tech Thursday.
Three teenagers attending a summer camp told authorities they saw a man carrying what looked like a long-barreled gun.
Virginia Tech activated its emergency messaging system, asking everyone on campus to seek shelter.
The warning system adopted after the 2007 massacre in which 32 people were killed and 25 others were wounded on the campus.
The school was criticized then for not issuing timely alerts that could have saved lives.
University officials make no apologies for issuing the alert this time even though no suspect was found, and it's not clear whether any law was broken.
"In this day and age I don't think we had any choice other than to issue a campus wide alert," said Virginia Tech's Larry Hincker.