A 15-year-old student killed a teacher and another student in a shooting at Abundant Life Christian School in Madison, Wisconsin, on Monday, police said.

Natalie Rupnow, who passed Samantha, also injured six other people – two were in critical condition, according to officials.

She had died of an apparent self-inflicted gunshot wound when police arrived at the scene around 11 a.m. Monday.

Rupnow attended the school with about 390 students in grades kindergarten through 12, police said.

“I don’t know if (the shooter) was transgender or not,” Barnes said at a news conference Monday night when asked about Rupnow’s gender identity.

“I don’t think what happened today had anything to do with how she or he or they wanted to identify,” he said. “And I wish people would leave their personal biases out of it.”

“Whether it was her or not, it was him, they were transgender, that may come out later – but what we’re doing right now, today, literally eight hours after a mass shooting at a school in Madison, it’s irrelevant right now.” said Barnes.

The teenage shooter used a handgun, police said. Authorities are investigating the source of the gun, Madison Police Chief Shon Barnes said.

They’re also talking to her father and “trying to figure out what he knew or didn’t know about what happened today,” Barnes said at a news conference Monday night.

“But again, he lost someone,” Barnes added.

A motive was unclear, he said, and it was not clear whether any of the victims were targeted.

However, Madison police are aware of an online document related to the incident and are reviewing it to learn more, Barnes said.

“A document about this shooting is currently circulating on social media, but we have not verified its authenticity,” Barnes said.

The family is cooperating, Barnes said, explaining that police do not currently intend to pursue charges in connection with the fatal shooting.

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

Police activity on Madison’s north side was confirmed to be related to the incident Monday afternoon. Later that evening, officials said it was the shooter’s home and authorities conducted a search.

The incident occurred shortly before 11 a.m. local time on Monday.

“The shooting occurred in a mixed-year study hall classroom,” Barnes said.

A second-grader called 911 as the attack unfolded.

“Let that sink in for a minute,” Barnes said. “A second grader called 911 at 10:57 a.m. to report a school shooting.”

Police believe the suspect was at the school when the attack began and there was no break-in.

However, investigators are investigating whether there were any possible warning signs, Barnes said.

According to a school representative, the school does not have metal detectors or a school resource officer, but does have other safety protocols in place.

Police confirmed that there were cameras installed inside the building.

The school representative also confirmed that faculty and students were trained in the lockdown procedures implemented during Monday’s active shooter incident.

On Monday evening, two of the six injured people were released from SSM Health St. Mary’s Hospital.

Two others were in stable condition, while two others were in critical condition with life-threatening injuries, officials said.

The identities of the victims have not yet been released.

This is a developing story. Please check back for updates.