A 15-year-old student killed a teacher and another student in a shooting at the Abundant Life Christian School in Madison, Wisconsin, on Monday, police said.
Natalie Rupnow, who went by Samantha, also injured six others -- leaving two in critical condition, according to officials.
She was dead of an apparent self-inflicted gunshot wound when police arrived on the scene at about 11 a.m. on Monday.
Samantha had attended the school along with some 390 students in grades Kindergarten through 12, police said.
The teenage suspect used a handgun, police said. Authorities are investigating the origin of the firearm, Madison Police Chief Shon Barnes said.
They are also speaking with her father and "trying to determine what he knew or may have not known about what happened today," Barnes said at a Monday evening press briefing.
"But again, he lost someone as well," Barnes added.
MORE: Abundant Life Christian School shooting in Madison: Teen student, teacher killed; 6 students hurt
A motive is not clear, he said, and it is not apparent if any of the victims had been targeted.
As of Monday evening, two of the six injured were released from SSM Health St. Mary's Hospital.
Two others are reported in stable condition, while two are in critical condition with life-threatening injuries, officials said.
MORE: 16-year-old in custody after suspected quadruple homicide of his family members
The incident took place shortly before 11 a.m. local time on Monday.
"The shooting happened inside a classroom in a study hall of students from mixed grades," Barnes said.
A second-grader called 911 as the attack unfolded.
"Let that soak in for a minute," Barnes said. "A second-grade student called 911 at 10:57 a.m. to report a shooting at school."
Police believe that the suspect was in school when the attack began, and that there wasn't any breach.
However, detectives are investigating whether there were any potential warning signs, Barnes said.
The suspect's family is cooperating, he said.
MORE: UnitedHealthcare CEO killing latest: Luigi Mangione expected to waive extradition, sources say
The school does not have metal detectors or a school resource officer, but has other security protocols in place, according to a representative from the school.
There are cameras inside the building, police confirmed.
The school representative also confirmed that the faculty and students had been trained in lockdown procedures, which were implemented during the active shooter incident on Monday.
The identities of the victims have not yet been made public.