Police in Nashville found out that the 28-year-old man who killed six people, including three children, at the Covenant School was transgender and had a detailed plan to attack the Christian school.

Officials said that Audrey Hale, a former student, shot her way into the school Monday morning through a side door.

Hale killed three 9-year-olds inside the school: Evelyn Dieckhaus, Hallie Scruggs, and William Kinney. He also killed a 61-year-old custodian, Mike Hill, a 61-year-old substitute teacher, Cynthia Peak, and the 60-year-old head of the school, Katherine Koonce.

After the shootings, Hale was killed by police on the second floor at 10:27 a.m., 14 minutes after the alarm was sounded.

Police said Hale had at least two assault weapons and a handgun, and when they searched her family’s home in Nashville, they found detailed maps and a plan for the attack.

“We have a manifesto and some writings that are still relevant,” said John Drake, chief of the Nashville Metropolitan Police Department, when asked about the find.

He also said that Hale was “ready to do more damage than was actually done” and that she had made plans to attack another school in the area but didn’t go through with them because the school was too safe.

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.

Hale was a well-known graduate of the small private Christian school, which has only about 200 students in pre-K through 6th grade, according to its website.

The school’s curriculum is based on biblical theology. Along with regular classes, students take classes about the Bible.

Drake told Lester Holt on NBC News Monday night that some people think there was some anger about having to go to that school. “Don’t know all the details about that yet, which is why this happened.”

Drake also said that once Hale got into the school by shooting through a locked door, she didn’t care who she shot.

“She went after students at the school at random…. “She shot at anyone she came into contact with,” Drake said.

Former headmaster Bill Campbell said, “I do remember her as a former student.” He said he had records of Hale as a third-grader at the school in 2005 and a fourth-grader in 2006, but after that she doesn’t show up in his yearbooks, so he thinks she must have moved.

Police said Hale had no criminal record or history of mental health problems. They are in touch with the suspect’s father and plan to release a video about the shooting in the next few days.

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

The Covenant School was started in 2001 as a ministry of the Covenant Presbyterian Church. Its annual tuition costs range from $7,250 for three-day pre-school to $16,500 for kindergarten through sixth grade.

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