Three students were killed and five others injured after a gunman opened fire on the Michigan State University (MSU) campus on Monday night.
The victims were all students at the university, police said, and the injured remain in critical condition.
The police said a caller’s tip led them to the suspected gunman, who died from a self-inflicted gunshot wound.
The suspect, who has since been identified, had no ties to MSU.
“We can confirm that the 43-year-old suspect had no affiliation to the university. He was not a student, faculty, or staff, current or previous,” Chris Rozman of the Michigan State University Police said.
Questions still remain about the motive of the gunman, who was identified as 43-year-old Anthony McRae.
“We have absolutely no idea what the motive was at this point,” Mr Rozman said.
The names of the victims have not yet been released.
Dr Denny Martin, the Chief Medical Officer of Sparrow Hospital, where the victims were taken for treatment, said four of the injured required surgery and one was taken to critical care. All five remain in hospital.
“This is something that we practice for very often, but never want to do,” said a visibly emotional Dr Martin at Tuesday’s news conference.
The gunman opened fire shortly before 20:30 local time (01:30 GMT) at Berkey Hall, a building located north of the MSU campus in the city of East Lansing.
Responding officers found multiple students who were injured – two of whom died on the scene.
Police said the suspect then walked over to the nearby MSU Union building, where they received several more reports of gunshots. The third victim died inside the building, they said.
The suspect then quickly fled the scene, sparking a large manhunt involving hundreds of officers.
He was found nearly four hours later at 11:45 local time in the City of Lansing, around three miles (4.82 km) northwest of campus, after police released a photo of him and a citizen called in a tip that helped locate him.
The photo, taken from surveillance footage, showed the suspect wearing a denim jacket, a navy baseball cap and red trainers.
As the manhunt was ongoing, students were told to “shelter in place”. Some reported on social media that they were hiding.
One – Drew Russ, an 18-year-old from Los Angeles – was watching Star Wars with friends at his dorm when a deluge of text messages arrived.
He and everyone on his floor in the dorm, which is about a mile from Berkey Hall, stayed put, he told MSNBC on Monday night.
“I couldn’t believe this was happening on my college campus,” he said.
Another student jumped out of a first-floor window at Berkey Hall, her parents said.
Mike and Natalie Papoulias rushed to the campus on Monday night from Jackson, Michigan, after receiving a call from their daughter, they told local media.
In a text message, the daughter said: “I heard somebody get shot, Mom. It’s terrifying. I could smell the gunpowder.”
City officials said the shooting has rocked the small communities of MSU and East Lansing.
“We went to school here, we got children here, we got family, this is us,” said Marlon Lynch, chief of campus police at the university.
All campus activities have been cancelled for at least 48 hours, said MSU president Teresa Woodruff, “to give ourselves time to think and to grieve and to be together”.
East Lansing lies about 70 miles (112km) north-west of Detroit.
At Tuesday’s news conference, Democrat House representative Elissa Slotkin of Michigan said she was “filled with rage” to be talking about yet another school shooting.
“The most haunting picture of last night was watching the cameras pan through the crowd and seeing a young person wearing an ‘Oxford Strong’ sweatshirt,” she said. The shirts were handed out to survivors of the Oxford High School shooting near Detroit, Michigan 15 months ago.
“We have children in Michigan who are living their second school shooting in under a year and a half,” she said. “If this is not a wake-up call to do something, I don’t know what is.”
In a statement, President Joe Biden said the victims in Michigan and those grieving other mass shootings are owed action on gun reform.
“The fact that this shooting took place the night before this country marks five years since the deadly shooting at Marjory Stoneman Douglas High School in Parkland, Florida, should cause every American to exclaim ‘enough’ and demand that Congress take action,” he said.
The shooting is the latest in a growing number in schools and college campuses across the US.
In November, three members of the University of Virginia football team were killed on campus, while 10 people were killed in a shooting at Umpqua Community College in Oregon in 2015.
In 2007, 33 lives were lost in a shooting at Virginia Tech.
Meanwhile, police in New Jersey said a town’s public and private schools were closed on Tuesday due to a threat connected to the Michigan State suspect.
A statement from the Ewing police department said its officers were informed the suspected gunman had ties to Ewing Township, and that a note containing a threat to two public schools there had been discovered