Authorities released footage of the 28-year-old female shooter arriving at a Nashville Christian school and walking around the building where she would gun down six people, including three children.

Footage from security cameras around the Covenant School building shows the shooter arrive on campus and drive around the building before entering the school by shooting through glass doors. The shooter then walks through the hallways, holding her assault rifle up as she opens doors and peeks around corners. While the video does not include sound, it appears the school’s alarms went off as lights began flashing in the hallways after the shooter broke the glass to gain entry.

WARNING: The video below does not show any of the moments when the gunwoman opens fire, but some readers may still find the footage disturbing.

The shooter, a woman who identified as a man in recent months, entered the school with three guns around 10:13 a.m. Monday, killing three adults, including the head of the school, and three 9-year-old children in what authorities described as a “targeted attack.” Police arrived 14 minutes later, and the shooter opened fire on arriving officers from a second-story window. The officers, however, made their way into the school before two Metro Nashville cops returned fire and killed the shooter.

On Monday afternoon, local authorities along with the FBI searched the home of the female shooter. During the search, law enforcement said they found “a manifesto” along with maps of the school drawn in detail that included points of entry. The police chief said authorities have a theory on the shooter’s motive, but they are not ready to share it yet.

Police identified the six victims, and they include three 9-year-old children and three adults 60 years old and above.

According to the Metro Nashville Police Department, the victims are “Evelyn Dieckhaus, Hallie Scruggs, and William Kinney, all age 9, Cynthia Peak, age 61, Katherine Koonce, age 60, and Mike Hill, age 61.” Katherine Koonce was the head of the Covenant School.

The Covenant School is a private Presbyterian school in Nashville’s posh Green Hills neighborhood that educates children from preschool through sixth grade. According to the school’s website, it enrolls between 195 and 210 students.