BERGEN COUNTY, N.J. - It was just after 10 in the morning on Sept. 6, 1949 when Philip Buxton flipped to the back of the phone book and found Howard Unruh’s number.

Buxton called. Unruh surprisingly answered.

Buxton, a reporter with the Camden Courier-Post staff, asked Unruh how many people he had killed.

“I don't know yet,” Unruh said, gun in hand, as police officers surrounded his apartment and took aim at his windows. "I haven't counted them, but it looks like a pretty good score."

In about 12 minutes that morning 70 years ago, the 28-year-old WWII veteran shot 16 people in his Camden neighborhood with a semi-automatic pistol. Thirteen would die. The youngest was 2; the oldest 68.

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Inside the shooter's mind

Some mass killers predated Unruh and had more victims. But none murdered so many in such a short time, the United Press reported that day.

Probably the first mass shooter to garner major media attention, Unruh displayed the same temperament reflected in many of his modern counterparts, said Katherine Ramsland, a professor of forensic psychology at DeSales University.

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Unruh was rigid, angry and blaming, said Ramsland, the author of "Inside the Mind of Mass Murderers: Why They Kill."

Frustrated by his circumstances in life, he used a firearm to act on his inner rage.

“When you add mental instability or paranoia, as we've seen in many other shooters, you have a recipe for anger boiling over into action,” Ramsland said. “Such people fantasize a lot, which become rehearsals for how they will fix the perceived problem.”

Unruh’s problem was with his neighbors.

After he was arrested, Unruh told police he felt disrespected by just about everyone in his Camden neighborhood. He found fault with nearly all the local shopkeepers over insults, perceived or real, the reports show.

“It's all about perception, fear and the need to act punitively or preemptively,” Ramsland said.

The description fits with many modern mass shooters, who have preyed on crowds in schools, entertainment venues, workplaces, churches, stores and other places where people of common background, interests or culture gather.

It fits with 21-year-old Patrick Crusius, who was charged with killing 22 people and injuring 24 others on Aug. 3 in the deadliest mass shooting in the nation this year.

Crusius told authorities that he had targeted Mexicans. He drove 650 miles from his Dallas Suburb to an El Paso Walmart with an AK-47, semi-automatic rifle and multiple magazines.

The 1949 shooting

Unruh did not travel as far. He just walked around the neighborhood.

Unruh admitted to prosecutors he had planned his assault early that morning. He picked 9:30 a.m., knowing the stores would be open and occupied by his intended targets.

After his mother cooked him breakfast, he loaded his Luger with an eight-round magazine and filled his pockets with spare ammo and a second clip. He had tear-gas cartridges, a pen gun launcher and a 6-inch knife.

Initial reports from the Courier-Post said the killings started with the pharmacist amid a clash over Unruh's use of a backyard gate.

However, Unruh told police he started by shooting 27-year-old cobbler John Pilarchik in his River Avenue shop. Without saying a word, Unruh said he fired into Pilarchik's chest and head.

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Unruh then strode next door into barber Clark Hoover’s shop. He silently shot Hoover, 33, and 6-year-old Orris Smith. Smith had been sitting on a white hobby horse for a hair cut. The next day was the first day of school.

As the first few shots rang out, Unruh’s mother Freda knew her son was involved. Earlier in the morning, Unruh had threatened her with a wrench, raising it above her head, after she approached him from behind as he prepared his weaponry in their living room, she later told the Courier-Post.

She fainted at a friend’s house a few blocks away.

The motive

Questions remain on what prompted Unruh’s rampage, known as the “Walk of Death.” Unruh told police it was a broken gate.

Patrick Sauer, a writer for Smithsonian magazine, reported in 2015 that Unruh was also bothered by a broken date.

On Sept. 5, Unruh went to the Family Theater on Market Street in Philadelphia, he told police. A known gay pick-up spot on Market Street, Sauer wrote, the theater was to be the meeting place for Unruh and a man with whom he was having an affair.

When Unruh returned home at about 3 a.m., he found the rear gate to his apartment missing, he told police. The recently-installed gate was designed to end an ongoing dispute with his pharmacy-owning neighbors, The Cohens. They had argued about the use of their gate and property to access the apartment.

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“It was building for two years or so, but this morning … when I came through the gate … I decided,” Unruh told police. “Our fence had been broken in two places, apparently done purposely. It was then I decided to do what I did.”

Ramsland said no single factor would have triggered Unruh’s rampage. It was a combination of his temperament and the circumstances, she said.

“He might focus blame on the gate, but he had a list of grudges. If it were just about the gate, he'd only have shot those responsible,” she said. “It was about feeling put-upon and possibly humiliated by his own life failures.”

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Known by neighbors as deeply religious, Unruh had attended Temple University’s pharmaceutical school for a couple of months in 1948 but dropped out citing poor physical condition. He was unemployed at the time of the shooting.

Unruh, who spent three years in an armored artillery unit in Europe during WWII, was subsisting on veterans’ assistance and by selling his model trains, he told police. His 25-year-old brother, James Unruh, told the Associated Press Unruh had been acting nervously since returning from the war.

He had a makeshift shooting range in the basement and molds to create bullets. In his bedroom, decorated with bayonets, pistols and trench art, was also a machete. Unruh told police he bought it to decapitate The Cohens. He also bought a book with bullet-making instructions.

The shooting

With his pockets still filled with those bullets, Unruh headed toward The Cohens' drugstore, also their home. James Hutton, Unruh’s 45-year-old insurance agent, briefly blocked his path. He would become Unruh’s fourth victim.

Once inside, Unruh killed Cohen’s wife, 38-year-old Rose Cohen, as she hid in a closet. He then shot 63-year-old Minnie Cohen, who attempted to call police, before he shot 40-year-old Maurice Cohen on the porch roof.

Back on the street, Unruh shot and killed 24-year-old Alvin Day as he waited at a red traffic light in his car, then 2-year-old Thomas Hamilton through an apartment window.

The tailor was to be next, Unruh said.

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After the killings, Unruh told police that Cohen, the pharmacist, as well as the barber, cobbler and tailor were all targets. He felt they were talking about him "because they didn't like" him, he said.

Unruh told police Cohen had insulted him by telling a customer Unruh was “allowing his mother to support him.” He said some shopkeepers said they would “gang up on” him and have him arrested, possibly for stealing some spare lumber to keep flooding out of shallow basement where he housed his pistol range.

He said the cobbler and the barber said they would soon give him a chance to use his gun. When he saw the broken gate, Unruh told police he thought the two were fulfilling their promise.

The tailor and victims

The tailor, Thomas Zegrino, was spared, but only because he left to run an errand. Unruh instead shot Zegrino’s bride of one month, 28-year-old Helga Zegrino.

After he found the local grocery barricaded, Unruh turned to a Chevrolet coupe at 32nd and River. He silently took aim. Three more shots killed Helen Wilson, 37, and her mother Emma Matlack, 68, and severely injured her son John Wilson, 9. The boy would later become Unruh’s 13th and final murder victim.

Three were wounded when Unruh entered a home at 942 North 32nd Street: 36-year-old resident Madeline Harrie, 36, her 16-year-old son Armand and Charles Peterson, an 18-year-old local. The latter was one of an estimated 2,000 people that rushed to the scene upon hearing the initial commotion.

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Out of ammo, Unruh ran home and locked himself in his second-floor bedroom. Police said Unruh must have emptied his pistol and refilled it at least four times during his "walk of death."

Once home, he greeted the swarm of police with more gunfire. The first patrolman on scene, John Ferry, was firing shotgun rounds at the second-story window when backup arrived with tommy guns, revolvers and tear gas.

Overwhelmed by the gas, Unruh surrendered.

Newspaper accounts said he was emotionless, perhaps even defiant, when booked that afternoon for the murders.

“I am glad I done it,” Unruh was quoted by the Courier-Post as telling police after the shooting. “The neighbors have been picking on me for months and when I came home last night and found my gate had been taken, I decided to shoot all of them so that I would get the right one.”

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Until his death in 2009, Unruh was Case No. 47,077 at the Trenton State Prison psych ward.

Controversially ruled criminally insane after the shooting, Unruh never stood trial. The charges against him were dismissed in 1980, with a Superior Court judge ruling he had been denied a speedy trial.

Follow David M. Zimmer on Twitter: @dzimmernews