Authorities yesterday said they have “no idea why” a 43-year-old gunman killed three Michigan State University students and wounded five in the latest US mass shooting, but said he had a history of mental health problems before the shooting spree that ended with him turning the gun on himself.

The 43-year-old gunman who killed three students and wounded five others at Michigan State University had no apparent connection to the campus, police said on Tuesday as they searched for a motive for shootings that terrified the community for hours.

Police said the note found in the pocket of Michigan State University shooter, Anthony McRae, indicated that "he felt he was slighted in some way from people or businesses"

Three people were killed and five wounded in shootings at Michigan State University late on Monday evening.

A gunman who opened fire at Michigan State University killed three students and wounded five, setting off an hours-long manhunt as frightened students hid in classrooms and cars.

As authorities search for a motive in the shooting at Michigan State University by a gunman who had no known connection to the school and who later killed himself, university police on Tuesday identified the three students killed.