NASHVILLE, Tenn. (WKRN) — Three children, three adults, and the suspect were killed in a shooting at a school in the Nashville neighborhood of Green Hills on Monday morning. Surveillance video shows the shooter shot their way into the campus.

The shooting happened at The Covenant School, a private Christian school with an enrollment of about 200 students from preschool to sixth grade. It was initially reported as an “active shooter” incident at 10:13 a.m., Nashville police spokesperson Don Aaron said.

When police entered the school’s first story, they heard gunshots coming from the second floor, Aaron said. They immediately “went to the gunfire,” he said, where they found the suspect armed with two assault rifles and a handgun and firing.

Three children and three adult staff members were shot and killed, police confirmed in a press conference.

Metro Nashville Police confirmed all three children were 9 years old, identifying them as Evelyn Dieckhaus, Hallie Scruggs and William Kinney. Authorities also identified the staff members as Mike Hill and Cynthia Peak, both 61 years old, and Dr. Katherine Koonce, 60.

One police officer sustained a hand injury from broken glass. There were no additional injuries.

Metro police released photos Monday night, showing a bullet hole in a squad car windshield, along with windows shot out from the second story of the school. Police say the suspect fired shots at arriving officers from the second floor.

Police said two officers entered the building, ran toward the sound of gunfire, met the suspect on the second floor of the school, and fatally shot them. Those officers have since been identified as Rex Englebert, a four-year MNPD veteran, and Michael Collazo, a nine-year MNPD veteran.

Aaron initially said the shooter appeared to be a teenager, but police later identified them as 28-year-old Audrey Hale from Nashville. Investigators say Hale was a former student of the school who identified as transgender.

Police gave unclear information on the gender of the shooter. For hours, police identified the shooter as a 28-year-old woman, then eventually identified the person as Hale. Then at a late afternoon press conference, the police chief said Hale was transgender. After the news conference, police spokesperson Aaron declined to elaborate on how Hale identified.

During a Monday evening press conference, Drake said authorities are still working to determine a motive but that detailed maps with information on surveillance and entrances were found after the shooting.

A manifesto and writings believed to be related to the shooting are also being reviewed. Authorities have spoken with Hale’s father.

Drake said in an interview with NBC News that investigators believe the shooter had “some resentment for having to go to that school.”

The Covenant School was founded as a ministry of Covenant Presbyterian Church in 2001, according to the school’s website. The school is located in the affluent Green Hill neighborhood just south of downtown Nashville, situated close to the city’s top universities and home to the famed Bluebird Café – a beloved spot for musicians and songwriters.

The grade school has 33 teachers, the website said. The school’s website features the motto “Shepherding Hearts, Empowering Minds, Celebrating Childhood.”

The killings come as communities around the nation are reeling from a spate of school violence, including the massacre at an elementary school in Uvalde, Texas, last year; a first grader who shot his teacher in Virginia; and a shooting last week in Denver that wounded two administrators.

President Joe Biden, speaking at the White House on Monday, called the shooting a “family’s worst nightmare” and implored Congress again to pass a ban on certain semi-automatic weapons.

A reeling city mourned during multiple vigils Monday evening. At Belmont United Methodist Church, teary sniffling filled the background as vigil attendees sang, knelt in prayer and lit candles. They lamented the national cycle of violent and deadly shootings.

“We need to step back. We need to breathe. We need to grieve,” said Paul Purdue, the church’s senior pastor. “We need to remember. We need to make space for others who are grieving. We need to hear the cries of our neighbors.”

The Associated Press contributed to this report.