Lansing, Mich. — Although neighbors in Lansing describe the man police say was the Michigan State University gunman as generally quiet, they told CBS Detroit’s Andres Gutierrez gunfire was a common occurrence in the backyard of his father’s home.

Authorities say McRae killed three students and wounded five others Monday night before shooting himself to death when he was confronted by police off-campus, near his father’s house. Police say he wasn’t affiliated with the school and they’re searching for a motive.

Neighbors say they often heard McRae shooting target practice in the backyard.

“And he’s always popping off and rounds — ‘Pop, pop, pop, pop, pop, pop, pop pop’ — all (the) time in the summer and I’m like, ‘What’s going on?'” said one neighbor, Ray.

“We didn’t even think about it, you know, other than we’ve heard the shots and stuff and we’d be like (what) the heck? . … But we didn’t have any issues. Like, he wasn’t out there in the street going crazy or anything,” said Megan Bender.

Police are trying to figure out what triggered McRae to carry out shooting. Authorities didn’t know where he was until they released surveillance photos and someone recognized him.

Ray believes it was the outfit that made it easy.

“You don’t see people wearing that. And I knew exactly who he was. And if he didn’t — if I didn’t hear that call from my brother that he took his own life, I was calling the police in two seconds,” Ray said.

One neighbor, Fransico, said the tragedy has floored him and he hopes there are more answers soon.

Authorities say MaRae had a criminal history involving firearms and was on probation for 18 months for possessing a loaded gun in a vehicle.

Police found a note in his pocket indicating a threat to two schools in Ewing Township, New Jersey, where he had ties, the district’s superintendent said in a statement posted online.