When the calls for help came in and police were deployed, nobody was expecting to find a female shooter at Abundant Life Christian School. Nearly all mass shootings during the past 40 years have been carried out by boys or men. Her 9mm pistol was in line with what is used in a majority of mass shootings, about twice as often as rifles or shotguns.
Evidence suggests that the 15-year-old shooter, identified as Natalie "Samantha" Rupnow, died by suicide, and authorities say her family has been cooperative with investigators.
"We have initiated the search, but we think that search is either ongoing now or that search may be concluded," Madison Police Chief Shon Barnes said.
The teenage suspect used a handgun, police said. Authorities are investigating the origin of the firearm, Barnes said.
A motive is not clear, Barnes said at a news conference. It is also unclear if any of the victims was specifically targeted, officials said on Monday.
Police ID 15-year-old girl as alleged Wisconsin school shooter
The suspect's father is speaking with police at one of their facilities.
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 law enforcement search of her home is aimed at collecting computers and other personal electronics that will help establish the shooters so-called "digital fingerprints."
Police are also looking to the suspected shooter's social media for clues.
Investigators also need to rule out whether Rupnow had help in pulling off the 11 a.m. attack, or even just provided information to friends or family about a plan for violence.
Police ID girl, 15, as alleged Wisconsin school shooter who killed 2
"We do not know that the shooter had any prior contact with law enforcement," Barnes said. "We, you know, we're not going to interrogate students. We're going to give them an opportunity to come in and speak to what they may have seen when they feel ready."
Not only is the fast response by police to an active shooter call now an accepted and expected tactic, there is also a police template for post-mass shooting investigations.
"Why did this happen? What do we know? What was the motivation? I do not know. But, I will tell you this, our detectives are working hard on the investigative process to find out as many answers as we can so that we can further prevent these things from happening, not only in this community, but in other communities around our country," Barnes said.
A teacher and teenage student were killed, and six were hurt in a shooting at Abundant Life Christian School in Madison, Wisconsin, on Monday, police said.
ABC News contributed to this report.