Virginia Tech, the site of a 2007 massacre where 33 people were killed, was locked down early Thursday, after a man was seen with a gun.

In a notice posted on the school's Web site, the university advised people on campus to stay indoors and secure doors. Three juveniles attending a camp at the university reported seeing a man holding what appeared to be a gun at 9:09 a.m. local time. The man was seen outside of New Residence Hall East heading toward the volleyball courts.

A person with a gun was later seen near the Deitrick dining center, according to a subsequent alert, reports Bloomberg.

The Virginia State Police sent six units to assist the school in locating the man, and the FBI also sent agents. Virginia Tech Police Chief Wendell Flinchum announced at 11:35 a.m. local time that officers continue to question people and search for the man, reports the Richmond Times-Dispatch.

At 2:41 p.m., administrators lifted the lock down, so the campus could resume normal activity.

In 2007, student Seung Hui Cho went on a two-hour rampage, killing 32 people before taking his own life.

Sources: Bloomberg, Richmond Times-Dispatch