BLACKSBURG, Va. — Virginia Tech lifted a campus lockdown Thursday afternoon after an extensive police search for a man with a gun supposedly seen by three teens turned up empty.
"The campus alert is lifted. There will continue to be a large police presence on campus today," the university said in a notice posted at 2:41 p.m. "Police have not received nor discovered additional information about a person possibly carrying a weapon beyond that reported this morning."
The 2,600-acre campus, site of a 2007 mass shooting that left 33 people dead, was ordered locked down at 9:37 a.m. after three girls about age 14 told authorities they had seen a man walking hurriedly on campus carrying what appeared to be a gun covered with a cloth. The girls were attending a summer camp on campus.
The university told students and employees to stay inside and secure doors and classes were canceled for the remainder of the day "out of an abundance of caution," Larry Hincker, associate vice president for university relations, said at a news conference.
Officers searched the campus and found no one matching that description.
Virginia Tech Police Chief Wendell Flinchum told reporters at an afternoon press conference that police had interviewed the youths and determined that their report was credible.
"They gave us a good description. We felt it was best course of action to issue a campus alert," Flinchum said.
"I think the girls believed what they reported. The officers believed they (the girls) believed what was reported and that’s the information they went with."
Regular classes aren't in session but several thousand students are on the Blackburg campus attending summer classes at the school.
The girls who reported seeing the gunman were attending a Higher Achievement Program academic camp on campus.
Higher Achievement CEO Richard Tagle said a group of 9- to 14-year-olds were on campus for the camp and Thursday was the last day.
Flinchum said the girls reported seeing the man near Dietrick Hall, a three-story dining facility. The dining hall is steps away from the dorm where the mass shootings took place in 2007.
They described the man as white, 6 feet tall, wearing a blue-and-white shirt and gray shorts and brown sandals. He was reported walking fast in the direction of the volleyball courts.
Flinchum said police have not received any other sightings of the man.
The campus was the scene of the deadliest mass killing by a lone gunman in U.S. history — the April 16, 2007, shooting spree by Seung-Hui Cho that killed 32 people and wounded 25 others before the gunman committed suicide.
Virginia Tech, which was criticized for not reacting quickly enough in that case, responded quickly this time.
After sending out an initial warning on the Web site, the school continued to update people on campus and the city of Blacksburg kept its citizens apprised of the situation through its own Web site.
Federal authorities fined the school in March after ruling that administrators violated campus safety law by waiting too long to notify staff and students about a potential threat after the first two students were shot to death in 2007, in West Ambler Johnston Hall, a dorm near the dining facility.
An email alert went out more than two hours later that day, about the time Cho was chaining shut the doors to a classroom building where he killed 30 more students and faculty and himself.
The school's alert system also was activated in 2008, when an exploded cartridge from a nail gun produced sounds similar to gunfire near a campus dormitory. It was the first time the system was activated after the 2007 massacre. After the shootings, Virginia Tech started using text messages and other methods besides emails to warn students of danger.
Carrying a gun on campus isn't necessarily illegal.
The Virginia attorney general's office says "a public university generally cannot prohibit open or concealed carry of a firearm on campus grounds," even though a university can ban openly carried guns in campus buildings or at specified events.
But the state attorney general has determined that public universities cannot bar gun owners with valid concealed carry permits from bringing firearms into campus buildings.
Reuters, The Associated Press and NBC's Pete Williams contributed to this report.