Officials said Audrey Hale, a former student, entered the school Monday morning by shooting through a door on the side of the building.

While inside, Hale killed Evelyn Dieckhaus, Hallie Scruggs and William Kinney, all age 9, as well as custodian Mike Hill and substitute teacher Cynthia Peak, both 61, and school head Katherine Koonce, 60.

Following the shootings, Hale was killed when they encountered officers on the second floor by 10:27 a.m., 14 minutes after the alarm was raised.

Police said Hale was equipped with at least two assault weapons and a handgun, and in searching her family home in Nashville, officers found detailed maps and a manifesto of the attack.

“We have a manifesto, we have some writings that we’re going over that pertain to this day,” Nashville Metropolitan Police Chief John Drake said about the discovery.

He added that Hale was “prepared to do more harm than was actually done,” and that she had drawn up plans to attack another school in the area, but backed out of them because the school was too secure.

Asked whether Hale’s identity could be a factor in the motive, Drake said authorities “feel that she identifies as trans, but we’re still in the initial investigation into all of that and if it actually played a role into this incident.”

In online profiles, Hale had indicated they used he/him pronouns and also went by the name Aiden.

It is unclear whether Hale identified as a man or woman at the time of the slayings.

Follow The Post’s coverage of the school shooting in Nashville

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• School shooter’s parents ‘couldn’t accept’ their daughter’s trans identity: report

Hale was notably an alumnus of the small, private Christian school, which teaches students in pre-K through 6th grade and only has about 200 students enrolled, according to its website.

The school focuses its curriculum on biblical theology, where students take classes about the Bible along with standard education courses.

“There’s some belief that there was some resentment for having to go to that school,” Drake told NBC News’ Lester Holt on Monday evening. “Don’t have all the details to that just yet and that’s why this incident occurred.”

Drake also said Hale had been indiscriminate with whom she targeted once she had entered the school, by shooting through a locked door.

“She targeted random students in the school. … Whoever she came in contact with, she fired rounds,” Drake said.

Former headmaster Bill Campbell said “I do remember her as a former student” and that he had records of Hale as a third-grader at the school in 2005 and a fourth-grader in 2006, but said after that, she does not appear in his yearbooks and he thought she must have transferred.

Police said Hale had no police record or record of mental health problems and that they are in contact with the suspect’s father and plan to release video about the shooting in the coming days.

Police also released pictures of the weapons Hale used, two assault rifles and a handgun.

The Covenant School was founded in 2001 as a ministry of Covenant Presbyterian Church and its annual tuition fees range between $7,250 for three-day pre-school and $16,500 for pupils in kindergarten through sixth grade.

The school focuses its curriculum on biblical theology, where students take classes about the Bible along with standard education courses. Its motto is “Shepherding Hearts, Empowering Minds, Celebrating Childhood.”

The school is located in the affluent Green Hills neighborhood just south of Nashville’s Bluebird Cafe, a beloved spot for musicians and songwriters.