The suspected shooter, 43-year-old Anthony Dwayne McRae, lived in Lansing, officials said.

The shooter died of a self-inflicted gunshot wound as law enforcement was approaching, a law enforcement source briefed on the situation said.

The source added that a firearm was recovered at the scene, and a second firearm was found in a backpack along with numerous magazines.

McRae served 18 months in prison between 2019 and 2021 on a weapons charge for having a loaded weapon in his vehicle, according to Michigan’s Department of Corrections.

-ABC News’ Lucien Bruggeman, Luke Barr and Josh Margolin

At Michigan State, students and staff are overcome with shock, fear and confusion, Lansing Mayor Andy Schor told ABC News’ “GMA3.”

“It's a terrible time. No mayor, no governor, no elected official ever wants to be up all night or wake up to a situation like this,” he said.

Schor said mental health resources are available.

Schor said the five injured students “are critical but stable.”

“It’s touch and go,” he said. “and the doctors are doing their best to work as aggressively as possible.”

When the suspect, 43-year-old Anthony McRae, was found dead from a self-inflicted gunshot wound, authorities said there was a note in his pocket indicating a threat to two public schools in Ewing, New Jersey, according to Ewing police.

McRae had local ties to Ewing but hasn’t lived in the area in several years, police said.

Ewing Public Schools are closed on Tuesday out of an abundance of caution, police said. However, no threat has been found and schools are expected to reopen on Wednesday, police said.

McRae “had a history of mental health issues,” police added.

No motive is known, police said. The 43-year-old suspect, Anthony McRae, had no affiliation with MSU, university officials said.

After police released the suspect’s photo, a tip from a caller led authorities to finding him, officials said.

When he was confronted, he took his own life," Lansing Mayor Andy Schor told ABC News’ “GMA3.”

A search warrant has been executed at a home, police said.

The suspect in Monday's mass shooting at Michigan State had two 9 mm handguns and additional magazines and ammunition on him when he was found dead from a self-inflicted gunshot wound, Michigan State University Interim Deputy Chief Chris Rozman said at a news conference Thursday.

The guns were purchased legally but were not registered, Rozman said.

The suspect, 43-year-old Anthony McRae, was found dead about 3.8 miles from the MSU campus on Monday night, Rozman said.

McRae had a two-page note that listed threats against Michigan State, two New Jersey schools, and 13 local businesses, including a Meijer grocery store chain warehouse where he had previously worked, Michigan State Police said.

Body camera video showed McRae did not say anything to officers before he died by suicide, authorities said.

Police said they interviewed McRae's father who indicated that his son rarely left his room and had no friends.

Marlon Lynch, MSU’s vice president for public safety and chief of police, commended the students who helped render aid to their classmates when gunfire erupted in Berkey Hall.

Four of the injured students were in critical condition and one was in stable condition on Thursday, officials said.

Their names have still not been released.

-ABC News’ Alex Perez and Whitney Lloyd