Nashville police revealed on Monday that a 28-year-old's lethal assault on the private Christian school they once attended may have been driven by a sense of "resentment." Audrey Hale, a Nashville resident, had no prior criminal record before initiating the shooting at The Covenant School, which resulted in the deaths of three children and three adults, according to authorities.

Metropolitan Nashville Police Chief John Drake told NBC News' Lester Holt that there is some suspicion that resentment over attending the school played a role in the attack. Police have discovered detailed maps and surveillance, indicating that Hale meticulously planned the assault.

Although the shooter appeared to have targeted The Covenant School, Drake did not confirm that Hale had intended to attack specific individuals. He also mentioned to NBC News that there were signs that Hale had other locations in mind for potential attacks.

Among the victims was Covenant's head of school, 60-year-old Katherine Koonce. Drake explained that Hale randomly targeted students in the school, firing rounds at anyone she encountered. To enter the school, she shot open a locked door.

Officials are examining writings and a map left by the former student, which detail the plan for the attack. Drake also confirmed that Hale was transgender, but it remains unclear whether this factored into the incident.

Bill Campbell, former headmaster of the school, recalled Hale as a third and fourth-grader in 2005 and 2006. He expressed deep sorrow over the tragedy caused by the former student. Campbell believes Hale transferred after the fourth grade, as she was not listed as a student in the yearbooks for fifth or sixth grades.

Campbell did not remember any issues with Hale during her time at the school that could have raised concerns. He described her as a typical student who was loved and appreciated like all other students.

Police Chief Drake stated that Hale arrived at the school armed with two AR-style weapons and a handgun. Two of these weapons were legally obtained in the Nashville area. Five officers confronted Hale, and two of them fired their weapons, killing the attacker. A car near the scene helped police identify the shooter, and investigators are now searching Hale's residence.

Authorities noted that Hale's writings indicated The Covenant School was not her only intended target. Drake praised the responding officers for their swift action, which prevented a potentially worse outcome.

Nashville Mayor John Cooper also commended the first responders, emphasizing that their courageous efforts under fire saved lives.