Once again Thursday, police rushed to the campus of Virginia Tech. Again, the words, "man with a gun," raced across the university. And again, students and workers locked doors and turned off lights.
But a daylong search failed to locate the tall figure in the blue and white vertically striped shirt whom a group of summer campers thought they saw with a pistol, and by late afternoon their report remained unconfirmed.
A five-hour campus lockdown was lifted shortly after 2:30 p.m.
Still, this was Virginia Tech, where in 2007 a deranged student armed with two handguns killed 32 people and himself, and such reports resonate as perhaps nowhere else.
"We're in Blacksburg," said Alex Watt, 19, a sophomore from Springfield, Va., who was on campus Thursday. "And because of the history, it makes it scarier."
The initial report came in at about 9 a.m., when three 14-year-old girls attending an academic summer camp said they saw a 6-foot-tall white man, in gray shorts and sandals, walking quickly with what looked like a handgun concealed by a cloth.
Text and email alerts went out quickly across the university, which was populated by only a few thousand summer school students, researchers and other employees, and athletes.
Staff members went through buildings to spread the alert orally.
"Person with a gun reported near dining hall," an alert posted at 9:37 a.m. read. "Stay Inside. Secure doors. Emergency personnel responding. Call 911 for help."
The university also asked anyone with information to call a campus police tipline.
Police flooded the campus, and a composite drawing of a boyish-looking man with spiky, light-colored hair was generated.
By midday, officials had canceled all summer school classes for the day and had asked that people stay away from campus.
But four hours after the initial sighting, police had not found a gunman. Police said no other witnesses came forward to say they had seen him.
"We have interviewed several persons similar in description to that provided by witnesses this morning," campus Police Chief Wendell Flinchum said in an afternoon statement. "None of those subjects are the person described."
Police had questioned the three campers further and deemed their information credible, Flinchum said.
Virginia Tech revamped its alert system after the 2007 shootings.
A university official said Thursday that more than 48,000 students and campus personnel received a text message alert and that an email alert was sent to every student and school employee.