Major Brown led a largely solitary life, his family said.

The 29-year-old, who suffered from schizophrenia, mostly sat by himself each day outside the family’s Cate Avenue home.

So his death by gunfire Wednesday night remains a mystery.

The incident started with a loud, insistent knocking on the front door at 9 p.m. Someone was asking Brown for a light while his family was upstairs preparing for bed.

He ran upstairs to his sister’s room for a lighter, ran back down and outside the house. And then about five shots rang out.

Family members found him seconds later, shot multiple times and sprawled on the grass outside. Authorities pronounced Brown dead at the scene, said Cpl. Don Coppola, a police spokesman.

“It just feels like a dream, and I haven’t woke up yet,” said Alma Brown, 48, his mother. “I’m used to him coming into my room checking on me. He always checked on the house at night, but all that’s over with.”

Her son spent most days at their 12345 Cate Ave. home, sitting on a plastic crate near the front door, she said.

He stayed at home partly because his illness affected his job prospects. He once was a janitor at a local elementary school, but the school dismissed him in 2012 out of concerns he was too mentally ill to work, Alma Brown said. He heard or saw things and took medication.

His sister, Barbara Brown, 26, said he’d often spend long stretches sitting in the bathtub in the dark.

On Wednesday night, Alma Brown listened from upstairs while her son answered the door. She could hear him say, “I don’t have a light, I don’t smoke.”

He ran upstairs and grabbed a lighter from his sister before racing back down.

Then the gunfire erupted. At least one bullet struck something metallic. The shots were so loud that Alma Brown said her ears were ringing.

As they ran downstairs, they saw the front door was wide open. Alma Brown found her son just around the home’s side near a cluster of plastic bicycles for toddlers, just past their waist-high metal gate, flat on his back with his arms out past his head.

A green plastic cup he was carrying when he answered the door had rolled out of his grip and come to rest beyond his hands.

“I started screaming, ‘Oh Lord, they killed my baby,’ ” Alma Brown said.

Police on Thursday had no other details on their investigation, other than urging anyone with information to call Crime Stoppers at (225) 389-3845 or (225) 389-STOP.

“I’m just scared, ’cause I don’t know who did it,” Barbara Brown said.

She could think of no one who would want to harm her brother.

Each morning, he would go outside to sit on the plastic milk crates, talking to a friend or two on a cellphone, Barbara Brown said.

More recently he would sit atop the Ford Cutlass he bought with savings in September, even though the car had a tarp over it, and look out at passing traffic, she said.

He needed money for a driver’s license, and told his sister he planned to apply for one on Thursday.

He never got to drive the car.