EAST LANSING, Mich. >> The man who shot eight students at Michigan State University, killing three, was found with two handguns and a note containing a possible motive for the attack, police said Thursday.

The 9 mm guns, dozens of rounds of ammunition and the two-page note were found with Anthony McRae when he killed himself Monday night after being confronted by police, said campus deputy chief Chris Rozman.

Investigators said they still were trying to pin down a motive, three days after the violence at the 50,000-student campus in East Lansing, but the note was a key point.

“It appears based on the content of the note that he felt he was slighted in some way by people or businesses,” Rozman said at a news conference. “Did a mental health issue amplify that or was it a component of that? We’re not sure at this point. We’re working our best to try to determine that as best as possible.”

McRae, 43, was the lone shooter and had no connection to the victims or to Michigan State as a student or employee, police said.

Rozman described the investigation as “massively complex.”

The shootings happened Monday during evening classes at Berkey Hall and nearby at the MSU Union, a social hub where students can study, eat and relax. Students across the vast campus were ordered to shelter in place for four hours — “run, hide, fight” if necessary — while police hunted for the gunman. Some residence halls were a mile away from the shooting scenes.

Students have described breaking windows and taking other desperate steps to escape Berkey Hall, which will stay closed through the spring term.

McRae walked nearly 4 miles (6 kilometers) toward his Lansing home after the shootings and said nothing before killing himself in front of police, said Lt. Rene Gonzalez of the state police.

McRae’s father, who shared the house, told police that “his son does not have any friends,” Gonzalez said. “He pretty much sat in his room most of the time.”

McRae had a misdemeanor gun conviction in 2019, though it didn’t bar him from having the handguns, which Rozman noted were purchased legally but not registered.

The students who died were from suburban Detroit: Brian Fraser, 20, Arielle Anderson, 19, and Alexandria Verner, 20.

One of the five wounded students was upgraded to stable condition at Sparrow Hospital. The others remained in critical condition but with “signs of improvement,” interim university President Teresa Woodruff said.

Two of the students are from China, according to a statement from the Chinese Consulate in Chicago.

Classes remain suspended through the weekend, Woodruff said.

The briefing by police followed a Wednesday night vigil on campus that drew thousands of students. Tom Izzo, the university’s revered basketball coach and father of a student, offered words of comfort.

“Our hearts are heavy. Our loss has been great. Our lives have been permanently changed,” said Izzo, head coach since 1995. “But with a shared commitment to help each other, and a promise to remember those we have lost, we will learn to find joy once again.”

Associated Press journalists Ed White in Detroit and Ao Gao in Los Angeles contributed to this report.