The truck pulled up to the Holland Tunnel headed to New York City at around 8 a.m. Tuesday.

It could hardly have been more conspicuous.

Emblazoned with emergency lights, neon green accents, crosshairs on each door, snippets from the Constitution and the name of a Pennsylvania gun range, the truck quickly drew the attention of Port Authority police.

Cops noticed a crack in the front windshield, according to NBC4. When they looked more closely, they spotted ammunition on the front seat.

Inside the souped-up truck, authorities discovered a small arsenal: five pistols, an AR-15 assault rifle, a 12-gauge shotgun, ammunition, half a dozen knives and body armor.

Some of the weapons were loaded, authorities said.

Police arrested the truck’s owner, John F. Cramsey, as well as its two other occupants: Dean S. Smith and Kimberly Arendt. All three were charged with illegal possession of guns and ammunition.

Authorities say three people were arrested with a cache of weapons, some loaded, after police stopped them near the Holland Tunnel in New Jersey June 21.

The arrest made national headlines. The truck was headed from New Jersey into downtown Manhattan, and would have emerged barely a mile from Ground Zero. The arrest also came just nine days after the deadly mass shooting in Orlando.

“3 Arrested With Multiple Loaded Guns, Knives, Body Armor at Holland Tunnel on Way to NYC,” ran NBC4’s headline.

The New York Police Department’s counterterrorism chief tweeted that his department was “monitoring the events unfolding.”

New York City’s Joint Terrorism Task Force was called, according to ABC.

But the trio’s true intention wasn’t terrorism, according to Arendt’s mother.

“They were trying to help,” Michele Plocinik said.

Plocinik told The Washington Post that her daughter had received a startling text message Tuesday morning from a young woman who said she was on heroin and in trouble in New York City.

Arendt recruited Cramsey, owner of the gun range, to help her save the woman, Plocinik said. Both Arendt and Cramsey belong to a group devoted to fighting heroin addiction. Smith tagged along to film.

They were arrested just a few miles from their mission.

“I know for a fact they weren’t going to shoot anybody,” Plocinik said. She said she understood the concern over the guns, but said the media had made a “mess” of the situation and authorities were wasting their time.

“They are going after the wrong people,” Plocinik said of police. “These people were trying to help people on drugs. Now they are all sitting in jail.”

Arendt, who also goes by the last name Walker, and the two men will appear in a Hudson County, N.J., courthouse Wednesday morning to be formally arraigned, NBC4 reported. At that time, their lawyers will have a chance to explain what Plocinik called “a big misunderstanding.”

For those who know John Cramsey, however, his arrest hasn’t exactly come out of the blue.

When police removed evidence from his truck, they came across an ammunition container that hinted at his own personal struggle — and at his anger.

“Shoot your local heroin dealer,” said a neon green message on the ammo box.

Cramsey’s road to his arrest at the Holland Tunnel began back in February.

That’s when his own family was shattered by heroin.

On Feb. 20, authorities found the bodies of Cramsey’s 20-year-old daughter, Alexandria, and her boyfriend inside an Allentown, Pa., row-house.

The couple had overdosed on heroin, Cramsey said at a community meeting six weeks later.

During the meeting, the 50-year-old grieving father took umbrage when the Lehigh County Deputy Coroner said each autopsy on a suspected overdose victim cost taxpayers $2,500 to $3,000.

“You’re telling me my daughter’s life isn’t worth $3,000?” Cramsey shouted, according to the Morning Call.

He then told a panel of prosecutors, law enforcement officials, counselors and a doctor that the community needed help in its fight with heroin dealers.

“They’re selling poison,” Cramsey said.

“This is a plague and we are losing our brightest and most brilliant minds,” he told the newspaper.

Cramsey’s solution was “Enough is Enough,” a group he co-founded after his daughter’s death to combat Pennsylvania’s raging heroin crisis. Alexandria Cramsey’s suspected overdose was one of 10 such deaths in a two-week period, Morning Call reported.

Cramsey began promoting events and anti-heroin messages on his Facebook page.

“Training tonight for properly administering Naloxane,” he wrote on June 1, alongside pictures of his daughter. “The lessons you learn might just give you the tools to save the life of somebody closer to you than you would ever think possible. …”

“Nothing will ever change until we ALL have the courage to stand together and shout out loud,” he wrote. “ENOUGH is ENOUGH!”

Some of his Facebook posts were more menacing, however. In some, he pointed high-powered assault rifles at the camera at threatened drug dealers. Several posts made it appear he was waging a one-man war on heroin mongers.

“Word on the Streets says that you F—— have put a ‘Bounty’ out on my A–,” he wrote on June 10. “Bring it … I’d be more than happy to introduce you to my daughter. LET THE PURGE BEGIN.”

Five days later, Cramsey posted photos of himself sitting in his vehicle on an apparent stakeout.

“It’s about 3:00 am in the morning,” he wrote. “Comfy ? Do you know where your children are? Unfortunately if they’re not in their room … I know where they are.”

“I’m getting really tired of just waiting around already,” he continued. “Who wants to Play a Game of … Knock … nw.”

Cramsey seems well aware that his harsh tactics were controversial.

“I will never change who I am or what I believe in to appease the people who do not agree with my ideology or way I do things,” he wrote on June 20. “You only hate me because you wish you could get them.”

The next day, Tuesday, marked four months since his daughter’s death.

It was also the day Kimberly Arendt called.

Arendt had been planning an “Enough is Enough” fundraising concert when she got the girl’s alarming text message some time after midnight Tuesday morning.

Arendt, a 29-year-old single mother living in Lehighton, Pa., had lost “quite a few friends” to heroin, her mother said.

“She got a message from somebody she thought was on drugs and needed help,” Plocinik told The Post, adding that her daughter knew the girl from a juvenile camp for at-risk youth where Arendt had worked in the past.

Arendt contacted Cramsey.

“We’ll go out and get her and bring her to her family,” he told her, according to Plocinik.

Dean Smith, a 53-year-old videographer, tagged along to film the mission, Facebook posts show.

Several hours later, at 7:13 a.m. Tuesday, Cramsey posted photos to Facebook showing him, Arendt and Smith in Cramsey’s truck on the way to New York.

“I’m currently 11 miles outside of Brooklyn, New York and going to a hotel to extract a 16 year old girl who went up there to Party with a few friends,” Cramsey wrote on his group’s Facebook page. “One of those friends she went up there with will not be returning. This young lady from Wilkes Barre [Penn.] is scared and wants to come home. Last night she woke to find her friend’s body next to her in the same bed.”

“Who remembers the Beastie Boys … NO … SLEEP … TILL BROOKLYN!” he added. “ENOUGH is ENOUGH! Coming to a Town near YOU SOON!”

When they arrived at the Holland Tunnel minutes later, however, Port Authority police spotted the ammunition and asked the driver — believed to be Smith — to get out of the car, then saw a handgun.

A search of the vehicle uncovered six more guns, including an AR-15 assault rifle and a 12-gauge shotgun, some of which were loaded.

Authorities also discovered less than 50 grams of marijuana and drug paraphernalia in the truck.

Cramsey told cops that he was coming to New York City to “rescue” the girl, according to ABC.

Instead, he was arrested. His mission was over before it began.

There might not have been a mission to begin with. According to ABC, the teenager supposedly at risk of overdosing alongside her friend in the hotel told authorities, “I don’t need to be rescued.”

Meanwhile, an employee at Cramsey’s gun range told the TV station that ever since his daughter’s death, Cramsey had been on a mission to spare others from the same fate.

Lyn Baker, who co-founded “Enough is Enough,” told the Daily Beast that Cramsey had started to go too far in the days before his arrest.

“About a week ago, he started posting very cryptic posts,” she said. “He felt like he was superman, like he could go and save these people.”

Baker said she, too, now expected legal trouble.

“I got a call from an attorney who said basically, ‘Brace yourself,’ because as a co-founder of the group, I will soon be under investigation,” she told the Daily Beast. “And I’m just a housewife, trying to save kids from heroin.”

Many of those who know Cramsey are now defending him, however.

One friend, John Berthel, said that driving around with guns is perfectly legal in Pennsylvania’s Lehigh Valley. Cramsey had made a “mistake” in crossing state lines with loaded weapons, however, he told the Daily Beast.

Michele Plocinik said Cramsey is a “great guy” with a “good heart.”

Despite the gun haul and the “crazy” headlines and the aggressive Facebook posts, Cramsey is not a vigilante, she said.

“This guy would never harm anybody,” Plocinik told The Post. She said she didn’t know how to explain the small amount of marijuana allegedly found in Cramsey’s truck.

Plocinik said her daughter had no criminal record other than a DUI and traffic problems, a claim born out by public records.

“To tell you the truth, I don’t even know if she’s ever shot a gun,” she said, adding that Arendt was “scared” and “a mess” after her arrest.

“These people are not bad people,” Plocinik said. “They are not terrorists.”

She said that in many parts of Pennsylvania, heroin is spreading while funding for treatment centers is shrinking. That leaves little recourse for desperate people.

Although worried about the charges facing her daughter, Plocinik hoped the incident might draw attention to their state’s heroin epidemic — a thought shared by many members of “Enough is Enough.”

“John, you told me you wanted ‘Enough is Enough’ to go nationwide,” wrote James Flamish on the group’s Facebook page. “Well it did.”