The shooter at a religious school in Wisconsin had two handguns with her but used only one in the attack that killed a teacher and a student and wounded six others, the city's police chief told The Associated Press on Wednesday.

Police were still investigating why the 15-year-old student at Abundant Life Christian Christian School in Madison shot and killed a fellow student and teacher on Monday, before shooting herself, Madison Police Chief Shon Barnes said.

Two other students who were shot remained in critical condition on Wednesday.

"We may never know what she was thinking that day, but we we'll do our best to try to add or give as much information to our public as possible," Barnes said.

The student who was killed was identified in an obituary released Wednesday as Rubi Patricia Vergara, 14, of Madison. She was a freshman and "an avid reader, loved art, singing and playing keyboard in the family worship band," according to the obituary.

The name of the slain teacher has not been released.

Barnes released the name of the shooter, Natalie "Samantha" Rupnow, hours after the shooting on Monday.

Barnes said the medical examiner would release the names of those killed, but state law prohibits releasing the names of the injured.

Police, with the assistance of the FBI, were scouring online records and other resources and speaking with the assailant's parents and classmates in an attempt to determine a motive, Barnes said.

Police don't know if anyone was targeted or if the attack had been planned in advance, he said.

While Rupnow had two handguns, Barnes said he does not know how she obtained them and he declined to say who purchased them, citing the ongoing investigation.

No decisions have been made about whether Rupnow's parents might be charged in relation to the shooting, but they have been co-operating, Barnes said.

Online court records show no criminal cases against her father, Jeffrey Rupnow, or her mother, Mellissa Rupnow. They are divorced and shared custody of their daughter, but she primarily lived with her father, according to court documents. Divorce records indicate that Natalie was in therapy in 2022, but don't say why.

Female shooters rare

The shooting was the latest among dozens across the U.S. in recent years, including especially deadly ones in Newtown, Conn.; Parkland, Fla.; and Uvalde, Texas.

But the Madison attack is an outlier as only about three per cent of all U.S. mass shootings are perpetrated by females, studies show.

School shootings have become a near-daily occurrence in the United States, with 322 of them this year, according to the K-12 School Shooting Database. That is the second highest total of any year since 1966 — topped only by last year's 349.

School shootings by teenage females have been extremely rare in the U.S., with males in their teens and 20s carrying out most of them, said David Riedman, founder of the K-12 School Shooting Database.

Emily Salisbury, an associate professor of social work at the University of Utah, studies criminology and gender. She said that females typically turn their anger on themselves because American culture has taught them that women don't hurt people, resulting in eating disorders, self-harm and depression.

It's difficult to speculate without knowing all the facts in Rupnow's case, Salisbury said, but a girl resorting to the level of violence she displayed suggests she experienced severe trauma or suffered violence herself.

"It takes more provocation, more instigation for girls and women to become violent," Salisbury said. "It's a very high probability she experienced some sort of violence in her life that can lead to serious mental illness."

Abundant Life is a nondenominational Christian school — prekindergarten through high school — with approximately 420 students.

Salisbury said the public shouldn't assume that the school's religious teachings mean its students are above bullying and ostracizing each other.

"They're children," Salisbury said. "As much as those [religious] values may be taught or discussed in the classroom in the culture of that school, kids are online all the time. Kids create their own culture through social media."