PONTIAC, Mich. — The parents of a 15-year-old boy accused of fatally shooting four classmates at a Michigan high school were taken into custody early Saturday, hours after they had been criminally charged, in an extraordinarily rare move to hold parents accountable when a minor uses their weapon in a school shooting.

Jennifer and James Crumbley were arrested after their car was spotted in a residential neighborhood in Detroit, Detroit Police Department spokesperson Rudy Harper told The Washington Post. The Crumbleys were briefly fugitives sought by local law enforcement and the U.S. Marshals Service.

Detroit police arrested the Crumbleys, who have been charged with involuntary manslaughter, after a local business owner noticed their vehicle. Authorities said that a woman fled on foot after police were alerted, prompting a search by law enforcement that involved K-9 units. The alleged shooter’s parents will be transported to a jail in Oakland County, Mich., and could be arraigned Saturday, said Undersheriff Mike McCabe of the Oakland County Sheriff’s Office.

Attorneys for the Crumbleys had said they left town the night of the shooting “for their own safety” and would return to be arraigned. But McCabe said earlier that the statement by the attorneys would not deter law enforcement from seeking them out and late Friday, U.S. Marshals released “Wanted” posters for the Crumbleys.

In announcing the involuntary manslaughter charges, Oakland County prosecutor Karen McDonald shared chilling new details about the behavior of the parents of Oxford High School shooting suspect Ethan Crumbley, in the days leading up to the rampage.

At a Friday news conference, McDonald revealed that teachers had twice raised concerns to the Crumbleys about their son in recent days — once, when he was seen searching for ammunition online during class, and again when a disturbing and violent drawing was found in his desk. In a meeting with school administrators just hours before the shooting Tuesday, the parents “resisted the idea of their son leaving the school” and did not tell school officials that Ethan had access to a gun, McDonald said.

McDonald also read social media posts from the family, describing how Jennifer Crumbley boasted on Facebook that they had bought their son his new Christmas present, a 9mm Sig Sauer SP 2022 pistol, last week. “My new beauty,” Ethan called it on Instagram.

The prosecutor called the parent’s actions “egregious” and “unconscionable,” saying they each face four counts of involuntary manslaughter. “While the shooter was the one who entered the high school and pulled the trigger, there were other individuals who contributed to the events,” McDonald said.

Authorities also disclosed new information about the gun on Friday: The pistol, purchased by James Crumbley on Nov. 26, was stored in an unlocked drawer in the parents’ bedroom, McDonald said. An employee of ACME Shooting Goods in Oxford, Mich., confirmed that Ethan accompanied his father for the purchase.

Jennifer Crumbley and her son both appeared to brag about the new gun in various social media posts McDonald cited. Shortly after his father bought the gun, Ethan Crumbley posted a photo of it to his Instagram page writing a caption interspersed with heart emoji that read, “just got my new beauty today, SIG SAUER 9mm. Ask any questions I will answer.”

Jennifer Crumbley captioned a post of her own on social media that read: “Mom & son day testing out his new Xmas present.” McDonald told The Washington Post that the post was a reference to a visit the two made to a gun range.

Three days after the gun was purchased — a day before the shooting — a teacher noticed Crumbley using his cellphone to search for information on firearm ammunition. Jennifer Crumbley did not respond when the school contacted her via voice mail about her son’s “inappropriate” search, McDonald said.

Instead, she exchanged a text message with her son that read, “LOL I’m not mad at you. You have to learn not to get caught.”

Oakland County Sheriff Michael Bouchard shared the first details about the weapon used in the deadly shooting at Oxford High School on Nov. 30. (AP)

The school’s concerns grew more acute the morning of the shooting. The Crumbleys had been summoned to a meeting by school administrators after a teacher found a troubling note in Ethan’s desk, McDonald said. It contained a drawing of a semiautomatic handgun pointing at the words “The thoughts won’t stop. Help me.”

Another section of the note had a drawing of a bullet with the words, “blood everywhere.” There was also a drawing of a bloody figure with two gunshot wounds, McDonald said, and another drawing of a laughing emoji.

Ethan altered the note, McDonald said, scratching out the most disturbing parts of it by the time the meeting with his parents began shortly after 10 a.m. on Tuesday. McDonald said the teen brought his backpack to the counselor’s office and noted that at no point did his parents ask about the recently purchased gun. McDonald said neither the Crumbleys nor school officials searched the teen’s backpack.

The Crumbleys “resisted the idea of their son leaving the school at that time,” McDonald said. Instead, Ethan returned to class with his backpack.

Less than three hours later, the first 911 calls poured in about shots fired at the school.

“Ethan, don’t do it,” Jennifer Crumbley texted to her son when news of the active shooting went public, McDonald said. Moments after the text, McDonald said James Crumbley drove home to check on his son’s gun kept in the couple’s bedroom. When he found it missing, he called to report it to 911 and said his son might be the shooter.

David Chipman, a veteran Bureau of Alcohol, Tobacco, Firearms and Explosives agent once nominated to lead the agency, said if prosecutors find evidence the shooter’s parents acted unlawfully, the criminal justice system has a duty to act.

“As gun owners, we have a responsibility that when we acquire firearms, we don’t put our neighbors, and in particular their children, at risk,” Chipman said. “If a parent provided their car to an unlicensed teen for a night of drunken joyriding, no one would be shocked if a prosecutor sought to hold the adults accountable.”

When asked if school officials could face charges, McDonald would only say that the investigation is “ongoing.”

“Looking at that drawing, it’s impossible not to conclude that there was a reason to believe he was going to hurt somebody,” McDonald said.

Determining whether a student’s disturbing behavior constitutes a true threat is enormously challenging for school officials. Some experts said Friday they could not blame Oxford officials for failing to grasp the deadly threat they faced. Others, though, said warning signs were clear and officials should have checked the student’s backpack for weapons and barred him from the school building based on his drawings alone.

“It certainly sounds as if there were very, very serious warning signs that should have been taken much more seriously,” said David Rourke, director of training for QBS, a company that offers training for school districts across the country in how to prevent violence and handle behavior issues.

But administrators face a burdensome challenge assessing which students would act on threats since many more never do, said Ronn Nozoe, executive director of the National Association of Secondary School Principals.

“It’s hard to tell if they need someone to talk to or they are ready to carry out horrific acts,” he said. “It’s easy to armchair quarterback that. In the fog of the moment, it’s much harder to untangle it.”

McDonald noted the gun shop owner is not under investigation as the elder Crumbley purchased the gun legally; in Michigan, children can be at gun stores and shooting ranges if supervised by parents.

McDonald on Friday rejected the idea she was trying to set a new standard for prosecuting mass shootings and said she has “tremendous compassion and empathy” for parents whose children have struggles that may precede an incident like this.

“I am by no means saying that an active-shooter situation should always result in a criminal prosecution against parents,” she said. “But the facts of this case are so egregious.”

The charges filed against the Crumbley’s come as school shootings are on the rise, and as prosecutors are seeking new tools to hold parents of schools shooters accountable.

The Crumbleys have shared little with investigators or the public, declining to let investigators question their child when he was first detained.

The family’s small, pale-green house on a quiet street has been dark and vacant in recent days; neighbors, relatives and former employers have declined to discuss the family or have not responded to requests for comment.

But social media posts and other online information about the family lend some shape to their lives.

YouTube videos posted by a chipper, 10-year-old Ethan Crumbley in 2016 showed the family vacationing in Michigan’s Upper Peninsula, where they strolled next to Lake Superior and visited a bear zoo. Other videos posted on Facebook by James Crumbley, which have since been taken down, showed him pranking his wife by pretending to have gotten an electric shock and both parents daring Ethan Crumbley to eat a dollop of horseradish.

Neither parent appeared to be involved in political activities. But in 2016, Jennifer Crumbley posted on her blog an admiring open letter to former president Donald Trump, who had just been elected.

She described herself as a Realtor and “the opposite of your typical ‘republican’” — a pro-choice feminist who supported the LGBT community and did not believe in God. But she also thanked Trump for “allowing my right to bear arms,” which she said allowed her to “be protected if I show a home to someone with bad intentions.”

Elsewhere, she described herself as an animal lover and runner; complained to a local paper about potholes; and created a Pinterest board with ideas for decorating Ethan Crumbley’s room. A state website indicates that her real-estate-sales license lapsed in 2018.

The Crumbleys made a brief virtual appearance at their son’s Wednesday arraignment where he faced 24 charges: one count of terrorism causing death, four counts of first-degree murder, seven counts of assault with intent to commit murder and 12 counts of possession of a firearm in the commission of a felony. They appeared side-by-side briefly, before turning off their cameras for the remainder of the hearing.

In Michigan, gun owners are not required to lock up their weapons or keep them away from children, according to Giffords Law Center. Even in the 30 states that have passed some form of a child-access protection law, researchers say, the laws are often not enforced and the penalties are weak.

Charging parents of juvenile shooters is uncommon, with just four reported instances in which the adult owners of the weapons were criminally punished because they failed to lock firearms fired by a child, according to an analysis of all school shootings between 1999 and 2018 by The Post. That’s despite the fact that if children as young as 6 did not have access to guns, well more than half of the country’s school shootings since 1999 would never have happened, The Post found.

“If you look at school shootings, the overwhelming majority are committed by students, and the overwhelming majority of those students have guns that they brought from their homes or a relative’s home,” said Daniel Webster, director of the Johns Hopkins Center for Gun Violence Prevention and Policy.

The four known prosecutions of parents did not stem from charges related to negligent-storage laws. The harshest penalty among those cases was a sentence of more than two years in prison for a man charged with involuntary manslaughter after a 6-year-old boy found his gun in a shoe box and killed a classmate.

Following a number of copycat threats in the days after the rampage, authorities launched investigations into other students, including one into a 15-year-old junior at a nearby high school, who was arrested Thursday on a charge of making a terrorist threat. Authorities, who say the student threatened to shoot up the school if he could get a gun, removed several guns from his home, Oakland County Probate Referee Michael Hand said.

Laura Meckler, Griff Witte, Mark Berman and Amy Cheng contributed to this report.