Victim ... Ethan Schmidt, 39, has been shot dead at Delta State University in Mississippi. Picture: Delta State University

Delta State University was locked down as a massive number of police officers search for Professor Shannon Lamb, 45, who is considered armed and dangerous.

Lamb‘s girlfriend, believed to be Amy Prentiss, was found dead in the city of Gautier, Mississippi, on the morning of September 14. Lamb contacted Gautier Police to inform them of the death and then drove 480km south to the university in Cleveland and shot dead his colleague, history professor Ethan Schmidt, in his office.

Lamb allegedly believed the woman killed was also in a relationship with 39-year-old Professor Schmidt, Fox News reported.

Suspect ... police said Professor Shannon Lamb, 45, is armed and dangerous over the shooting murders of a colleague and history professor at Delta State University and earlier, his girlfriend. Picture: Delta State UniversitySource:Supplied

Reports of Schmidt’s shooting sent the campus into a lockdown and all lessons were cancelled for the remainder of the day.

“Fortunately for us, our public safety officers and university officials have trained many of us for active shooter situations,” Don Allan Mitchell, an English professor, wrote in a Facebook message to The Associated Press. “Many students are locked-down in classrooms, and professors and staff members are telling them the protocol. Plus, we are all texting and Facebooking each other to make sure we are safe.”

Law enforcement personnel pored over the grounds in search of the gunman.

When asked how the shooter could escape the victim’s building so quickly, Cleveland Police chief Charles Bingham said the victim’s office was close to an exit and “it was not hard to leave the building rapidly.”

Professor Shannon Lamb is an avid musician, who plays in a rock and roll two-piece band that gigs across Mississippi. Picture: FacebookSource:Facebook

Professor Shannon Lamb is deemed 'armed and dangerous' after shooting dead his girlfriend and a university colleague. Picture: FacebookSource:Facebook

Lamb was believed to be driving a 2011 black Dodge Avenger with a Mississippi license plate STF015.

Lamb was among a long list of colleagues that Schmidt, who is married with three children, thanked in his 2014 book Native Americans in the American Revolution.

“We are grieving on this campus with this loss, and our condolences are with the family at this time,” Delta State University Relations Vice President Michelle Roberts said in a statement.

Law enforcement officers gather on the Delta State University campus to search for Professor Shannon Lamb after he shot dead history professor Ethan Schmidt in his office. Picture: AP / Rogelio V. SolisSource:AP

On Lamb’s Facebook page in April 2013, the professor wrote that he was a single parent to a teenage boy and girl. Lamb said about his children that “both are straight ‘A’ students, extremely loving and respectful of others.”

Lamb, a geography professor at Delta State, has worked at the school for seven years, according to his official profile. His profile adds that he teaches World Regional Geography, Methods in Social Studies, and Social Studies in the High School.

Professor Ethan Schmidt, 35, was married with three children. Picture: Delta State UniversitySource:Supplied

Schmidt worked at Delta State University since 2013 after teaching for six years at Texas Tech University, according to his biography on the university’s website. He received the President’s Award for Excellence in Teaching in 2011.

Delta State University is one of eight publicly funded universities in the state of Mississippi. There are 3,324 students at the school.