A manhunt is under way after a gunman shot dead a professor as he worked in his university office in Mississippi.
Ethan Schmidt, a history teacher at Delta State University, died in the attack in the city of Cleveland.
The suspect, geography professor Shannon Lamb, is on the run and has told police "he's not going to jail".
Police say he is armed and dangerous, and are linking him to the fatal shooting of a woman 300 miles away earlier in the day.
Amy Prentiss, 41, was found shot dead at her home in Gautier, Mississippi, in the early hours.
At a news conference on Monday evening, police in Gautier said they had spoken to Lamb, 45, who has been an employee of the university since 2009.
They did not say how they made contact with him but they urged the public to be extremely careful if they spotted him. He is thought to be driving a Dodge Charger.
The university is about a five-hour drive north, and police were called there at 10.18 local time (16:18 GMT) when shots were heard.
Prof Schmidt, who specialised in Native American and colonial history, was shot in his office inside the university's Jobe Hall building, police said.
All campus buildings were then locked from the inside and officials advised people to shelter as police cleared students from buildings on campus.
Freshman Noah Joyner, 18, said he stayed inside a bathroom in his dorm buildings during the lockdown.
"There were people banging on the doors to have somebody let them in," he said. "It was pretty terrifying to hear people banging on the door."
Police helicopters were circling the campus and hundreds of officers swept the buildings.
Lamb was apparently "easy going" and had taken some leave recently for "personal reasons", Don Mitchell, an associate professor of English at the university, told Fox News.
He called Prof Schmidt "a gentleman in every sense of the word" and "a terrific family man".
Roughly 3,500 students are enrolled at the university near the Arkansas border.