LeMoyne-Owen College President Johnnie Watson says 18 students were in the English classroom when the man barged in Thursday.
Watson says the man - who had a handgun - ordered students to toss their purses and wallets on the floor. He then fled the campus. No shots were fired and no one was hurt.
Police searched the campus and the surrounding, inner-city neighborhood but made no immediate arrests. The campus was temporarily locked down and classes were canceled for the rest of the day. The school has about 800 students.
Watson says the gunman was photographed by campus security cameras.