Law enforcement officers gather on the Delta State University campus to search for an active shooter in connection with a the shooting of history professor Ethan Schmidt in his office in Cleveland, Mississippi, Sept 14, 2015. [Photo/IC]

JACKSON, Miss. - A Mississippi college professor was shot and killed in his campus office on Monday, and police said a fellow Delta State University teacher was "a person of interest" in the shooting.

Authorities said they were searching for geography and social science instructor Shannon Lamb in connection with the killing of Ethan Schmidt, an assistant professor of American history.

Lamb was also a suspect in the killing of a woman in Mississippi earlier on Monday, police said.

The shooting left students and staff at the Cleveland, Mississippi, school on edge for several hours as police locked down the campus and searched buildings following reports of active gunfire.

Cleveland Police Chief Charles "Buster" Bingham told an afternoon news conference that authorities did not believe Lamb was still on the campus, which is near the Arkansas-Mississippi state line.

The killing was the latest in a series of shootings on US college campuses in recent weeks, including deadly incidents at Sacramento City College in California, Texas Southern University and Georgia's Savannah State University.

Bingham would not comment on Lamb's possible connection to Schmidt.

Colleagues said they had no idea about a possible motive. "We're all clueless," said professor Charles Westmoreland, who taught history with Schmidt. "It's been a terrible day."

Westmoreland was teaching when he heard multiple shots coming from Schmidt's office. A swift and orderly evacuation followed, he said.

Lamb was also being sought in an earlier shooting in Gautier, a town 300 miles (480 km) south of Delta State on the Mississippi Gulf coast.

Gautier police detective Matt Hoggatt said Lamb, 45, was wanted in connection with the death of Amy Prentiss, 41, with whom he shared a home.