LITTLETON, Colorado—Minutes before he opened fire inside a Walmart on Wednesday, Scott Ostrem stormed down the stairs of his apartment building and told neighbors to “get the fuck out of his way. Then he got into his car and took off.”

Teresa Muniz says she gets a chill when she realizes her neighbor was on his way to commit America’s next horrific shooting. The “angry guy upstairs” drove to a nearby Walmart where witnesses say he walked in, calmly took out his handgun, and shot and killed three people waiting in line to pay. Neighbors described Ostrem as a bizarre, angry man who lived alone in an apartment with a stack of Bibles and virtually no furniture.

Marlena and Jason Fobb were checking out after buying a vacuum cleaner when they heard “pop, pop, pop.” A man in the line next to them fell to the ground bleeding.

The panicked couple left their credit card in the machine and ran for cover in the prescription glasses department where they huddled with five other people, including a baby.

“We were scared the baby would scream and the shooter would hear it and find us,” said Jason.

The Fobbs peeked out of the department window to see Ostrem nonchalantly walk by with a look that Marlena says was “like the devil. He was hell-bent on killing people.”

Ostrem fired another round of shots, the Fobbs said, before surveillance showed him leaving as quickly as he arrived.

Two men died in the store and a woman lost her life later at the hospital. The Adams County Coroner identified the victims as 52-year-old Pamela Marques of Denver, 66-year-old Carlos Moreno of Thornton and 26-year-old Victor Vasquez of Denver. Vasquez was the father of two daughters with another child on the way.”

Ostrem strolled out unharmed to the parking lot and disappeared.

Police who have been interviewing him would not comment on a motive. Ostrem made an initial appearance in a packed Adams County courtroom late Friday morning, but no charges have yet been filed. They are expected by Monday.

Law enforcement monitored the highways for Ostrem’s red Mitsubish Mirage hatchback all night without finding him. Then neighbors tell The Daily Beast they were shocked to see the fugitive returning home in his car. Teresa Muniz said when Ostrem saw police outside his apartment, he sped off. Soon after, Ostrem was apprehended at a stop light, wearing the same clothes he had on the night before. Looking gaunt and grim, the suspected murderer was arrested without incident.

Muniz says Ostrem appeared angry for the entire two years she lived downstairs from him.

“He never said hello. No one ever came to visit him and I thought that was strange.”

Hispanic residents said he was especially mean to them.

“He wouldn’t say nothing to us, but he talked to the only white couple who lives here,” Muniz said. “I don’t understand where that hatred comes from.”

Another neighbor who wished not to be identified got a look at Ostrem’s apartment after the building’s management asked the neighbor to board up windows broken out by SWAT.

“There was hardly any furniture in there except a TV, a lawnchair and a table. He slept on blankets on the floor,” the neighbor says, adding there were five Bibles on top and under the table.

The oddities weren’t confined to his apartment though.

Ostrem wore a karate suit, carried a bow and arrow, and often lugged a large Rubbermaid tub up and down the stairs, neighbors say.

“He did it three times a week every week. Up and down,” said Muniz.

Her boyfriend used to joke that there must be body parts inside.

Police say Ostrem had a “minimal” criminal history including a resisting arrest charge in 1999 and one for driving under the influence in 2003. Ostrem filed for bankruptcy in 2015 after he started an electronics business that failed after a year and a half.