“These guys were ready for a war,” said a motorist they tried to hijack.
They were wearing trenchcoats like the heroes of The Matrix sci-fi films.
The three - aged 18, 15 and 14 - had been planning to carry out “multiple homicides” since early this year, said New Jersey police chief Christopher Ferrari.
They “had planned on not being taken alive” by police, he added.
“We could have had a disaster here in Oaklyn,” said County Prosecutor Vincent Sarubbi.
The plot evoked memories of the 1999 massacre at Columbine High School in Colorado, in which two students killed 12 classmates and a teacher before committing suicide.
But the New Jersey trio were planning to randomly kill in the streets of their town of 4,400 people.
The plot was uncovered as the three set out on their mission armed with rifles, handguns, swords and knifes.
But they stumbled at the first hurdle, when an attempt to hijack a motorist failed and he went to the police.
Oaklyn police chief Ferrari said each was armed with a high-powered rifle or shotgun, and that they had handguns with more than 2,000 rounds of ammunition.
The weapons recovered also included swords and knives.
“It was sort of a Columbine-type thing, except they were going to be more mobile,” the police chief said.
Matthew Lovett, aged 18, was among those arrested. The younger two were not named.
Lovett also imagined an almost supernatural aura around himself, sometimes referring to himself as The Mystic, The One and Neo, friends said.
The One and Neo are names for Keanu Reeves’ character in The Matrix films.
“They kind of had that Matrix thing going on,” acquaintance Anthony Tesman said. “They would wear black glasses and slick their hair back.”
Investigations into the Columbine massacre also found references to Reeves’ Matrix character.
Ferrari said three of the targets were fellow students at the elementary-middle school, and that the next group of victims were to be chosen at random.
He said the three “indicated they had previous problems with students at Oaklyn Public School, and potential targets were students (there).”
“These individuals were planning on killing as many people as possible in a short time and creating widespread hysteria,” he said.
All three were charged with attempted murder, attempted carjacking and weapons offences. Lovett, who is accused of pointing a gun at the officer who arrested him, was also charged with aggravated assault.
Prosecutor Sarubbi said the weapons seized belonged to Lovett’s father and were legal.
Mathew Rich, who reported the carjacking attempt, said he was leaving for work when he saw the three dressed in trenchcoats and standing in front of a school.
One crossed the road in front of him then opened his coat to reveal a handgun, before signalling for his friends.
Rich said he drove around them, then notified the police.
When he returned to the area after driving to the police station, he saw the weapons being confiscated.