DENVER — The 20th anniversary of the attack at Columbine High School was supposed to be marked with prayers and memorials.
Instead, millions of parents, students and educators across Colorado awoke on Wednesday to news that an armed 18-year-old woman with an infatuation with the massacre had flown across the country to Colorado and that hundreds of schools had closed as a precaution as the authorities frantically searched for her.
By day’s end, the woman, a Florida high school student identified as Sol Pais, was discovered dead of an apparent self-inflicted gunshot wound in the mountains west of Denver.
Law enforcement officials said they had been worried by Ms. Pais’s determination: She bought a plane ticket, made the journey and bought a gun. John McDonald, the school safety executive director for Jefferson County Public Schools, which includes Columbine, called it a “pilgrimage.”
To many parents, the school closings and the frenzied manhunt drove fears that Columbine still had the power to captivate would-be attackers and that the community would never be free from the massacre, which took place on April 20, 1999, and left 12 students and one teacher dead.
“What does this mean for tomorrow and the next day?” asked Dana Gutwein, 34, who has a first grader and third grader in the Jefferson County Public Schools District, which includes Columbine. Ms. Gutwein was unsure whether she would immediately let her children go back to class when the hundreds of schools that had closed on Wednesday reopen.
“I’ve felt like I’m on the verge of throwing up since this started,” she said.
Across the Denver metro area, parents struggled to find the right words to explain the latest safety warnings to children who have grown up in an anxious era of lockdowns and active-shooter drills. At Columbine, students who were organizing a day of service to mark the 20-year anniversary saw their preparations eclipsed by emergency text messages from the school district, news alerts on their phones and dread.
“This week our message was supposed to be about love and recommitment,” said Rachel Hill, 17, a senior at Columbine. “But now all the news surrounding Columbine is about fear.”
Some parents said they told their children to play close to home on Wednesday. Others shook their heads at how a threat from one teenager could keep half a million students home from school and throw an entire city into panic.
As the anniversary approaches, the threat and the fears have turned what was supposed to be a time of healing into a renewed source of trauma, said Urania Glassman, a clinical social worker and professor at Yeshiva University in New York.
“You have somebody who wants to throw a grenade on that parade and so do harm again,” Dr. Glassman said. “It retraumatizes people who were present and survived, it retraumatizes the families and it retraumatizes the communities.”
Even 20 years later, young people across America continue to be influenced by the symbology of the Columbine shooting and the students who carried it out, according to researchers and educators.
Law enforcement officials said that Ms. Pais, a student at Miami Beach Senior High School, had been “infatuated” with the Columbine shooting and had made alarming social media posts and threatening statements to friends and family.
On Monday, she flew from Miami to Denver and bought a pump-action shotgun and ammunition at a store in Littleton, not far from Columbine High School.
Colorado tightened its background check laws in recent years, but it does not have a set waiting period before buying a gun.
Ms. Pais’s parents in Surfside, Fla., reported her missing to local police on Monday. They provided investigators with information that helped them track her to Colorado, said Chief Julio Yero of the Surfside Police.
Law enforcement officials issued warnings on Tuesday expressing concerns about Ms. Pais’s mental stability and saying that she was armed and “extremely dangerous.” They launched what they called a “massive manhunt.” Schools across suburban Denver, already anxious about the approaching anniversary of the shooting, locked all their doors and stepped up security.
“We are used to threats certainly at Columbine,” said Mr. McDonald, the school safety director. “This one felt different.”
Sheriff Jeff Shrader of Jefferson County, Colo., said it did not appear that Ms. Pais had any help from friends in the area, just a fascination with Columbine and the horrendous crime that took place there.
At Miami Beach Senior High School, Katherin DeVargas Gil, a 17-year-old senior who took freshman Spanish and A.P. studio art with Ms. Pais this year, described her as “kind of in a corner.” Classmates said she was quiet and intelligent, but Ms. DeVargas Gil said a social media account with disturbing posts attributed to a Sol Pais had also made the rounds among her classmates.
“We talked about it in our first-period class,” Ms. DeVargas Gil said. “I even texted my mom, crying, saying I don’t want to be here.”
Brandon Bossard, a sophomore who had a second-period class with Ms. Pais, said she usually sat in chairs up against the classroom wall, alone.
“I didn’t believe it. I didn’t understand it,” he said. “She’s so quiet. How could someone so quiet be like that?”
Echo Lake Lodge
Echo Lake Lodge
An online journal that the authorities said they were investigating in connection with Ms. Pais read like a catalog of isolation, depression and anguish, illustrated with pictures of knives and guns. In a July 2018 entry, the journal writer described waking up every day feeling “lost, hopeless, angry, pissed off.” F.B.I. officials would not say on Wednesday whether they had determined if Ms. Pais was the author.
It was a tactical team from the Clear Creek County sheriff’s department that found Ms. Pais’s body, near Echo Lake, according to the sheriff, Rick Albers. According to the sheriff, Ms. Pais had taken a rideshare to a lodge by the lake.
At some point she had hiked about half a mile from the lodge, and then about 100 yards up a hill. She would have had to hike through snow to get there, somewhere between one and four feet deep, officials said. Clear Creek deputies found her by a stump, dead from a gunshot wound. She was in the same clothing the F.B.I. had reported her as wearing — boots, camouflage pants and a black shirt. She was also wearing a plaid jacket, and had a bag and a shotgun with her. Mr. Albers said that he did not know of any other guns found on her.
For some of the youngest students at home on Wednesday, the episode was their first introduction to the Columbine shooting, and to its legacy of worry and tripwire responses to threats to schools.
“It’s sad and scary,” said Jeff Desserich, a math teacher at a charter school in Denver, who spent the morning trying to explain to his daughters Anais, 8, and Elena, 6, why they would not be going to class.
“I said, ‘There is a lady, she probably has some sort of mental health issue,’” he said. “And I talked a little about the sad events of Columbine.”
Emily Fern, whose 5-year-old son and 4-year-old daughter go to school in Littleton, sat in bed on Wednesday morning debating whether to say anything at all to her children about why they were staying home. Her son, Hayden, loves Spider-Man and superheroes, so Ms. Fern decided to explain the threat in terms of “good guys” and “bad guys.”
Before leaving for her job as a hair stylist, Ms. Fern, 38, said she told her babysitter not to go farther than the front lawn of their cul-de-sac on Wednesday, and to run inside, lock the doors and call 911 if she saw anything suspicious.
“Just that feeling that she could be lurking in the neighborhoods,” Ms. Fern said of the threat. “You’re kind of looking everywhere.”
In Jefferson County, officials were making contingency plans to reopen schools, even if that meant overcoming logistical hurdles like changes in transportation and food service. “We did not wish to have one person hold all of the schools in the front range of the whole state hostage,” said Jason Glass, the schools superintendent.
Mr. Glass said even though those plans had not been implemented and schools would open on Thursday, they would be saved for the future.
Mr. McDonald, the school safety director, said the system did not want to play into the fascination with Columbine. “We’re not a place to come visit if you’re not a student,” he said. “We’re not a tourist attraction. We’re not a place for you to come and gain inspiration.”