Few official details about the gun violence were immediately available, but Chris Rozman, interim deputy chief of the university police, said shots were fired in two locations - at an academic building called Berkey Hall and the Michigan State University (MSU) Union building.
Police responding to the Monday night shooting found victims at both locations, Rozman told reporters at a televised briefing.
Rozman said investigators had no information about the motive. He also said the university was not aware of any threats made to the campus before Monday's bloodshed.
Rozman said three victims were killed and five were taken to hospital, some of them with life-threatening injuries. Two of the dead were at Berkey Hall and the other at the MSU Union.
Rozman said the suspect "was contacted by law enforcement off campus" at some point, adding, "that scene is being investigated as a crime scene."
The gunman was confirmed dead, from an apparently self-inflicted gunshot roughly four hours after the violence began, Rozman said.
"There is no longer a threat to campus. We believe there to be only one suspect in this incident," he said.
Students, faculty and residents in surrounding off-campus neighbourhoods of East Lansing, about 140 kilometres northwest of Detroit, had been told by authorities to "shelter in place" while the manhunt was on.
About three hours after the shooting erupted, MSU police released two still images of the suspect, taken by a surveillance camera, that showed him walking into a building, then mounting a short flight of stairs, wearing a jacket, jeans, a baseball cap and a black mask over his lower face.
MSU police said Monday night that all classes and school activities would be canceled for 48 hours at the university's flagship East Lansing campus, a sprawling public academic centre with 50,000 students, mostly undergraduates.
The violence came roughly 14 months after a deadly mass shooting on November 30, 2021, at Oxford High School in Oakland County, Michigan, about 130km east of East Lansing, in which a 15-year-old student opened fire with a semi-automatic pistol.
Four classmates were killed and six students and a teacher were wounded in that attack, the deadliest US school shooting that year.
Authorities said the teenage suspect in the 2021 shooting, who has pleaded not guilty to murder charges, used a gun his parents bought him as a Christmas present despite signs that he was emotionally disturbed.
Both parents were charged with involuntary manslaughter in the case.
Governor Gretchen Whitmer said on Twitter that she was being briefed on the East Lansing shooting.
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