The three victims were identified on Tuesday as Brian Fraser, a sophomore from Grosse Pointe, Michigan, Alexandria Verner, a junior from Clawson, Michigan, and Arielle Anderson, anther junior from Grosse Pointe.
RELATED | What we know about the Michigan State mass shooting victims
At a Tuesday night vigil, students not only grieved the lives lost and the classmates injured, but the shattered sense of safety at the campus.
"I'm a student at MSU, a place that I call home and feel safe, and it just made me feel bad that other people weren't able to be safe on this campus," said senior Nick Holycross.
"I was alone today. All of my friends have gone home and I'm not able to do that," said sophomore and international student Danni Vrattos. "I was just praying for community and I ran into these two individuals and they were lighting candles and they offered to let me come with them."
Officials do not know why 43-year-old Anthony McRae of Lansing targeted the campus. He was not a student or employee and had no affiliation with the university, according to campus police.
RELATED | Anthony McRae, suspected Michigan State University shooter, viewed himself as a 'loner,' FBI says
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The shooting began at 8:18 p.m. Monday night at an academic building known as Berkey Hall, and later moved to the nearby student union, a popular gathering spot for students to eat or study. Police said the gunman started shooting in one building and snuck to the other, as officers started arriving and investigators pushed out the suspect's photo.
A student inside the building where the first shots were fired said he did not get a good glimpse of the suspect.
"Right when that first gunshot went off, I booked it to the far corner of the class; I was sitting right next to the door, where he came in, literally one of the first two seats," Dominik Molotky said. "He came in, and thank God my fight of flight response kicked in because I booked it to the other side of the class and ducked down, and he came in and shot three to four times in our classroom."
He said some of his Cuban history classmates broke a window to get out.
"Honestly, I wasn't thinking anything, the first gunshot in the hallway got my ears ringing, and I just booked it down, took cover, then heard four more," Molotky said.
RELATED | Some MSU students critical of text message from school during shooting
The student said the gunman did not say anything before unloading his gun and going on to the next building.
"Everyone was quiet when the shots went off, but then, once he stopped shooting, that's when I think I heard one of my classmates start moaning," Molotky said. "Man, I'm lucky."
WATCH: Authorities ID MSU shooter
Authorities ID MSU shooter
As hundreds of officers scoured the East Lansing campus, about 90 miles northwest of Detroit, students hid where they could. Four hours after the first shots were reported, police announced the McRae's death.
"This truly has been a nightmare we're living tonight," said Chris Rozman, interim deputy chief of the campus police department.
Ryan Kunkel, 22, was attending a class in the Engineering Building when he became aware of the shooting from a university email. Kunkel and about 13 other students turned off the lights and acted like there "was a shooter right outside the door," he said.
"Nothing came out of anyone's mouth" for over four hours, he said.
WATCH: Officials provide update on MSU shootings
Officials provide update on deadly MSU shootings
"I wasn't ready to accept that this is really going on next door," Kunkel said. "This is supposed to be a place where I'm coming, learning and bettering myself. And instead, students are getting hurt."
RELATED | Michigan State University students recount deadly on-campus shooting: 'I was ducking and covering'
McRae was found with a note in his pocket indicating a threat to two schools in Ewing Township, New Jersey, where he had ties, that district's superintendent said in a statement posted online.
Ewing Public Schools closed for the day, but it was later determined there was no threat, Superintendent David Gentile said in the statement.
The shooting at Michigan State is the latest in what has become a deadly new year in the U.S. Dozens of people have died in mass shootings so far in 2023, most notably in California where 11 people were killed as they welcomed the Lunar New Year at a dance hall popular with older Asian Americans.
In 2022, there were more than 600 mass shootings in the U.S. in which at least four people were killed or wounded, according to the Gun Violence Archive.
"This is a uniquely American problem," Michigan Gov. Gretchen Whitmer lamented.
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Rozman, of the campus police, said two people were killed at Berkey Hall and another was killed at the MSU Union, while five people were in critical condition at Sparrow Hospital.
A hospital official said during a news conference Tuesday morning that four people underwent surgery, and all five remain critical.
Sparrow's Chief Medical Officer Dr. Denny Martin said he received a lot of texts from colleagues saying "I'm on my way; how can I help?"
Police eventually confronted the shooter after receiving a tip on where he was. He then died by a "self-inflicted gunshot wound" about 11:35 p.m., police said.
"We have no idea why he came to campus to do this tonight. That is part of our ongoing investigation," the deputy chief said.
Ted Zimbo said he was walking to his residence hall when he encountered a woman with a "ton of blood on her."
"She told me, 'Someone came in our classroom and started shooting,'" Zimbo told The Associated Press. "Her hands were completely covered in blood. It was on her pants and her shoes. She said, 'It's my friend's blood.'"
Zimbo said the woman left to find a friend's car while he returned to his SUV and threw a blanket over himself to hide for three hours.
During the manhunt, WDIV-TV meteorologist Kim Adams, whose daughter attends Michigan State, told viewers that students were worn down by the hourslong saga.
"They've been hiding, all the lights off in a dark room," Adams said.
WATCH: Police provide update on MSU shootings
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Police provide update after deadly MSU shootings
Aedan Kelley, a junior who lives a half-mile east of campus, said he locked his doors and covered his windows "just in case." Sirens were constant, and a helicopter hovered overhead.
"It's all very frightening," Kelley said. "And then I have all these people texting me wondering if I'm OK, which is overwhelming."
Michigan State has about 50,000 students, including 19,000 who live on campus. All classes, sports and other activities have been canceled, and classes will resume on Monday, February 20.
An official vigil will also be held to honor the victims Wednesday evening.
Some schools and East Lansing offices will also be closed.
Interim university President Teresa Woodruff said it would be a time "to think and grieve and come together."
"This Spartan community - this family - will come back together," Woodruff said.
The Bureau of Alcohol, Tobacco, Firearms and Explosives' Detroit division and FBI are on the scene.
President Joe Biden spoke with Whitmer about the shooting.
"President Biden and the First Lady are praying for the 3 killed & others injured in East Lansing," the White House press secretary tweeted.
Michigan officials give update after deadly shooting
Police ID MSU shooter, but motive remains unknown
The shooting at Michigan State is the latest in what has become a deadly year so far in the U.S.
Dozens of people have died in mass shootings so far in 2023.
Tuesday marks fifteen years since the shooting at Northern Illinois University in DeKalb, Illinois.
Five people were killed, and 17 others were injured when a gunman opened fire on that campus.
Bells will ring at 3:06 p.m. outside Cole Hall to mark that tragedy.
This also marks five years since the Parkland school shooting in Florida. A gunman murdered 14 students and three staff members at Marjory Stoneman Douglas High School.
The Associated Press contributed to this report.