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Sketch of possible Virginia Tech gunman released

Composite sketch of possible gunman seen on the Virginia TechTech University campus, Thursday, August 4, 2011

(CBS/AP) BLACKSBURG, Va. - Police have released a composite sketch of a possible gunman reportedly seen on the campus of Virginia Tech University Thursday morning.

Three children attending a summer camp on the Blacksburg, Va. campus said they saw a man holding what looked like a gun.

The campus remains on lockdown and people have been ordered to stay indoors. There haqve been no other reported sightings.Policeklice

The university issued the first alert on its website at 9:37 a.m. Thursday.

The children said they saw a man walking fast toward the volleyball courts, carrying what might have been a handgun covered by some type of cloth. Police swarmed the area but said they could not find a gunman matching their description. The university said on its website that no one else has reported a person with a gun or anything suspicious.

An alert on the school's website said the gunman was reported near Dietrick Hall, a three-story dining facility steps away from the dorm where the first shootings took place during the April 2007 massacre at Virginia Tech that left 33 people dead, including a student gunman.

Officials said the person they were looking for Thursday 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.