A day after a mass shooting on the campus of Michigan State University, authorities are investigating the motive for the rampage that left three students dead and five others wounded Monday night.

The gunman, who according to police had no known ties to the campus in East Lansing, Michigan, died from an apparent self-inflicted gunshot wound.

If you’re just now catching up, here’s what you should know:

The victims: Brian Fraser and Arielle Anderson, both from Grosse Pointe, Michigan, and Alexandria Verner, from Clawson, Michigan, died in the mass shooting Monday night, according to an MSU police news release. Verner was remembered by Clawson Public Schools Superintendent Billy Shellenbarger for her kindness, positivity and for being “everything you’d want your daughter or friend to be.”

MSU response: The first report of shots fired came at 8:18 p.m. ET from Berkey Hall, an academic building on the northern end of campus. Officers responded to the building within minutes and found several shooting victims, including two who died, according to MSU Interim Deputy Police Chief Chris Rozman. Immediately after that, another shooting was reported at the nearby student union building, he said. That’s where the third slain victim was found. As news of the mass shooting spread, anxiety permeated the campus as the gunman remained at large. A shelter-in-place order went into effect, MSU’s interim president Teresa Woodruff said.

Harrowing scene: The deadly rampage forced students to jump out of windows and run for their lives. Graham Diedrich, a graduate student at Michigan State University, recalled being in the library and using furniture with other students to barricade themselves in a room during the rampage. Michigan Attorney General Dana Nessel said her children, who are MSU students, are “shaken up” after the shooting.

The gunman: Authorities are still trying to figure out what prompted Anthony Dwayne McRae, 43, to conduct the shooting rampage. According to a source familiar with the investigation, McRae had a two-page note in his backpack that referenced other shootings. His father, Michael McRae told CNN his son became bitter, isolated and “evil angry” after his mother died from a stroke two years ago. The gunman’s sister told CNN her brother was socially isolated. McRae also has a criminal history with weapons, and police say he “had a history of mental health issues.”