CNN
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A group of Wisconsin police officers had planned to undergo training on Monday in caring for victims of mass trauma events when a second-grade student called 911 late that morning to report an active shooter at a nearby school in east Madison .

“They immediately left the training center and came here — and did what they were actually training to do in real time,” Madison Police Chief Shon Barnes said outside Abundant Life Christian School, where the shooting occurred.

When they arrived, officers performed life-saving measures on several people with gunshot wounds and found the shooter, 15-year-old student Natalie Rupnow, dead at the scene. Police say evidence suggests Rupnow, who went by the name “Samantha,” killed herself.

According to police, a teacher and another student were killed and six were injured, including two students who were hospitalized in critical condition.

The attack, which came just days before the Christmas holidays, has plunged the small, tight-knit community into mourning. According to the school’s website, students could look forward to a week of festivities, including a holiday concert and Ugly Christmas Sweater Day.

The tragedy marks the 83rd school shooting in the United States this year – surpassing 2023 for the most school shootings in a single year since CNN began tracking such incidents in 2008.

In interviews with CNN affiliate WISC, survivors of the attack – some as young as seven or eight years old – recalled screaming in the school hallways and saying they were “really scared” and “really sad.” Parents notified of the shooting said they were anxiously waiting to learn their children’s whereabouts.

“Thank God they were safe. But the trauma – it’s a lot because I’m sure they lost friends and teachers, which is not OK,” said Mireille Jean-Charles, a mother who has three children attending the school. “And I don’t think they’re going to be okay for much longer.”

As investigators continue to search the crime scene and a home in north Madison, they are also seeking additional search warrants. A motive behind the shooting remains unknown. Rupnow’s parents have cooperated with investigators so far, Barnes said, and will not be charged in connection with the shooting “at this time.”

“We will not be interrogating students,” Barnes said. “We will give them the opportunity to come in and talk about what they may have seen if they feel up to it, which is why some of these questions can’t be answered.”

Like all K-12 students, Rupnow entered Abundant Life at the beginning of the school day. Shortly before 11 a.m., while in a classroom filled with mixed-grade students, she pulled out a handgun and opened fire on her classmates, police said.

The school’s students, well trained in target practice, quickly realized the attack was real and “handled it brilliantly” despite being “obviously afraid,” said Barbara Wiers, director of elementary and school relations at Abundant Life.

As law enforcement waits for witnesses to come forward with new information, they are pursuing other leads to gain clarity on the timeline of events, clues that could determine Rupnow’s motive and details about the firearm she used.

Authorities were aware of writings posted by a person with alleged ties to Rupnow, Barnes said, but were unable to verify their authenticity. He said authorities have not located the person who made the post, but they are seeking help from the FBI.

A residential property in north Madison believed to be the suspect’s home was cordoned off and searched Monday, according to several neighbors interviewed, according to video from CNN affiliate WTMJ showing the main door of the building being opened House was removed and windows were blown out with stun grenades.

“I heard the news this afternoon and thought we’d just drive past Main Street and there it was,” a neighbor told WTMJ. “The front door was ripped off and no one was around and investigators are in there cleaning up the mess.”

Earlier Monday, Barnes said the suspect’s home had been searched and police were seeking additional search warrants. Rupnow’s father spoke to police at one of their facilities, he said. “We have no reason to believe at this time that they committed a crime,” Barnes said, referring to Rupnow’s parents.

In recent years, law enforcement has charged the parents of children who committed school shootings – for example, the father of 14-year-old Colt Gray, who committed a mass shooting at Apalachee High School in Georgia, was charged with 29 counts Earlier this year.

Police have asked the community not to hold vigils at the school as the school remains an active crime scene and was under surveillance overnight.

A candlelight vigil is planned for Tuesday evening and will be attended by the mayor and education officials.

Madison police are also expected to hold a meeting at 1 p.m. Tuesday where they could release the names and ages of the victims, including those who were hospitalized. Police had previously said they wanted to ensure all family members were notified before the victims’ identities were released.

In a statement released Monday, Wisconsin Gov. Tony Evers announced that all flags over federal installations and installations across the state would be lowered to half-staff through Dec. 22 in honor of the victims.

“As a father, grandfather and governor, it is unthinkable that a child or a teacher would wake up one morning, go to school and never come home,” he said. “This should never happen.”

The lockdown period for several county schools has been lifted and schools in the Madison Metropolitan School District will resume classes on Tuesday.

The fall semester is heading into Christmas break as it began – with a mass shooting.

Rice University in Houston, Texas witnessed an apparent murder-suicide on the first day of classes on August 26th. The following week, a 14-year-old gunman killed four victims at a high school in Winder, Georgia – making it the deadliest school shooting of the year.

The shooting at Abundant Life is also the latest shooting at a small, private Christian school — and one of 56 shootings that have occurred on the K-12 campus.

Last year, a shooting at Covenant School in Nashville, Tennessee, left three 9-year-olds and three adults dead.

Earlier this month, two boys, ages 5 and 6, were in critical condition after a shooting at a Christian school north of Sacramento in Oroville, California. Feather River Adventist School is a private school affiliated with the Seventh-day Adventist Church, a part of the Protestant Christian denomination whose followers believe that the Bible is the infallible word of God and the second coming of Christ.

CNN’s Jessie Yeung, Jennifer Feldman, Steve Almsay, Taylor Romine and Michelle Watson contributed to this report.