(AP, ABC7) The Virginia Tech lifted a campus-wide alert about five hours after a person with a gun was reported.
The alert was lifted at about 2:40 p.m. but the school reported that a large police presence will remain on campus.
Three teenagers from the D.C.-based non-profit Higher Achievement on a field trip to the school reported seeing a man carrying a gun. The university issued an alert on its website at 9:37 a.m. Thursday telling students and employees to stay inside and secure doors.
The alert said the gunman was reported near Dietrick Hall, a three-story dining facility. The dining hall is steps away from the dorm where the first shootings took place in the 2007 that left 33 dead.
A number of people matching the description of the suspect were stopped and questioned on campus, but ruled out, a campus official said.
The students provided police with information that was used to create a sketch of the suspect.
Higher Achievement, is a non-profit for middle school students, confirmed that its students were on the Virginia Tech campus at the time of the alert.
"Our first priority is the safety of our scholars and staff," Higher Achievement stated Thursday. "We have been in contact with them and we have received confirmation that everyone is safe, and are proactively reaching out to parents of students who were on campus. That is all the information we have at this time."
There were 145 students from the non-profit on campus during the incident and all were at school during the lockdown.
Police have not found any other people who saw the gunman. After 1 p.m., the school remained in lockdown.
"The university understands that it has been several hours since this began" the school stated on its web site. "Many officers from many police departments continue to search campus buildings. We have a very large campus and this will be a long process. There have been no further sightings or reports."
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 two students were shot to death April 16, 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 student Seung-Hui Cho was chaining shut the doors to a classroom building where he killed 30 more students and faculty and himself. It was the deadliest mass shooting in modern U.S. history.
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.
On Thursday, officials said they were looking for a 6-foot-tall white man with light brown hair. Officials said the person was wearing a blue and white striped shirt, gray shorts and brown sandals. He was described as clean shaven, according to the university's website.
Police from Virginia Tech, Blacksburg and Christiansburg searched for the man along with Virginia State Police and Montgomery County sheriff's deputies. FBI spokeswoman Dee Rybiski said agents also were on their way to assist.
To report any information, call the VT Police Department at 231-6411 or 911.
The students from Higher Achievement were on their way back to the D.C.-area and were expected back in the District by 7 p.m.