Officials are trying to figure out why a 15-year-old girl allegedly opened fire at the Christian school she attended, killing a fellow student and teacher in a heinous crime that shocked the community of Madison, Wisconsin.

The suspect, Natalie Rupnow, who went by Samantha, died of a self-inflicted gunshot wound before officers reached Abundant Life Christian School on Monday morning, police said. Officers did not fire their weapons.

Two students were hospitalized in critical condition with life-threatening injuries, police said, while another three students and a teacher suffered non-life-threatening injuries.

Police have not yet suggested any motive for the attack nor said whether they believe the victims were specifically targeted.

The suspect’s parents are cooperating with the investigation, Madison Police Chief Shon Barnes told ABC News on Tuesday.

“They were cooperative. Despite this tragedy, they still lost a child. They still lost a member of their family,” Barnes said. “It is certain that they have probably more questions than anyone because they knew her. They lived with her and so we wanted to get an account from them of what kind of child she was.”

Her father is being questioned by investigators, Barnes said. He said he didn’t know whether the mother had been questioned, noting that she’s been out of town.

Students in Kindergarten through 12th Grade attend the Christian school. Police said the shooting was contained to “a classroom in a study hall full of students from multiple grade levels.”

“I was in the hallway, and I was changing from my shoes to my boots to go to lunch because I have recess after, but then I heard the shooting and screams,” a girl in second-grade told ABC Chicago station WLS.

A second-grader also made the 911 call, Barnes said.

“Let that soak in for a minute,” Barnes added. “A second-grade student called 911 at 10:57 a.m. to report a shooting at school.”

President Joe Biden called the shooting “shocking and unconscionable” and called on Congress to act immediately.

Biden urged Congress to pass “commonsense” gun safety laws, including universal background checks, a national red flag law, and a ban on both assault weapons and high-capacity magazines.

“It is unacceptable that we are unable to protect our children from this scourge of gun violence,” Biden said in a statement, adding, “We cannot continue to accept it as normal.”

Biden also mentioned his administration’s efforts to combat the gun violence epidemic in the U.S., including the implementation of the White House Office of Gun Violence Prevention, while stating that more needed to be done.

Wisconsin Gov. Tony Evers said in a statement, “There are no words to describe the devastation and heartbreak we feel,” calling the shooting a “gut-wrenching tragedy.”

Evers said he and his wife are “praying for the families and loved ones of those whose lives were so senselessly taken and for the educators, staff, and the entire Abundant Life school community.”

“It is unthinkable that a kid or an educator might wake up and go to school one morning and never come home,” he said. “This should never happen, and I will never accept this as a foregone reality or stop working to change it.”

ABC News’ Briana Stewart contributed to this report.

Details are still emerging about the course of the Madison, Wisconsin, school shooting that left three people — among them the 15-year-old female shooter — dead and several others injured on Monday.

Police said that Natalie Rupnow, who went by Samantha, used a handgun to kill one teacher and one fellow student in the shooting.

Rupnow died of a self-inflicted gunshot wound before officers reached the school, police said. Officers did not fire their weapons.

Two students sustained life-threatening injuries and are in critical condition, while one teacher and two other students were treated for non-life-threatening injuries.

Police said in a Monday briefing that the shooting was contained to “a classroom in a study hall full of students from multiple grade levels.”

Police have not yet suggested any motive for the attack nor said whether they believe the victims were specifically targeted.

Madison Police Chief Shon Barnes said Monday, “I don’t know whether [the shooter] was transgender or not,” adding that the speculation as to Rupnow’s background was of no consequence to authorities at the time.

“I don’t think that whatever happened today has anything to do with how she or he or they may have wanted to identify,” Barnes added.

The suspect’s father reportedly spoke with police at one of their facilities shortly after the incident. Police are “trying to determine what he knew or may have not known about what happened today, but again, he lost someone as well,” Barnes said.

“The parents are fully cooperating, we have no reason to believe that they have committed a crime at this time,” Barnes said.

A second-grader made the 911 call, Barnes said. “Let that soak in for a minute,” Barnes added. “A second-grade student called 911 at 10:57 a.m. to report a shooting at school.”

President Joe Biden called the incident “shocking and unconscionable” in a statement Monday evening that called on Congress to act, “now.”

He insisted that they pass “commonsense” gun safety laws including universal background checks, a national red flag law and a ban on both assault weapons and high-capacity magazines.

“It is unacceptable that we are unable to protect our children from this scourge of gun violence,” the statement said, adding, “We cannot continue to accept it as normal.”

Biden also mentioned his administration’s efforts to combat the gun violence epidemic in the United States, including the implementation of the White House Office of Gun Violence Prevention, while stating that more needed to be done and offering his prayers to those affected in Madison.

Wisconsin Gov. Tony Evers said in a statement, “There are no words to describe the devastation and heartbreak we feel,” calling the shooting a “gut-wrenching tragedy.”

Evers said he and his wife are “praying for the families and loved ones of those whose lives were so senselessly taken and for the educators, staff, and the entire Abundant Life school community.”

“It is unthinkable that a kid or an educator might wake up and go to school one morning and never come home,” he said. “This should never happen, and I will never accept this as a foregone reality or stop working to change it.”