A shooter armed with two assault-style rifles and a handgun killed three students and three staff members at a Christian school in Nashville, Tennessee, on Monday morning, authorities said.
The suspect, identified by police as Audrey Hale, 28, of Nashville, had a detailed map of Covenant School, a school for students in preschool through sixth grade, and allegedly shot through the door to gain entry to the school, police said.
The children were identified by Nashville police as Evelyn Dieckhaus, Hallie Scruggs and William Kinney, all 9 years old. The slain adults were identified as Cynthia Peak, 61; Mike Hill, 61, and Katherine Koonce, 60, who was the head of the school, according to police.
Peak was a substitute teacher and Hill was a custodian, according to investigators.
The suspect was shot and killed by authorities in a lobby area on the second floor of the school roughly 14 minutes after the 911 call was placed, according to police.
Nashville Police Chief John Drake had said the suspect was female and identified as transgender but didn't immediately provide more details. A police spokesperson later told ABC News the shooter was assigned female at birth but pointed to a social media account linked to the shooter that included the use of the pronouns he/him.
Drake also said authorities believe the suspect was a former student.
No one who was shot survived, officials said.
Drake said he "was literally moved to tears to see" the young students as they were "ushered out of the building."
The suspect was armed with at least two assault-type rifles and a handgun, officials said. At least two of those weapons were purchased legally, investigators said.
The Metropolitan Nashville Police Department on Monday night released images of three weapons, as well as footage of the suspect driving and parking at the building, allegedly shooting through the door and walking around inside the facility while holding a gun.
The suspect had a map "of how this was all going to take place," and writings, according to Drake. It appears the shooting was a targeted attack, according to the chief.
Authorities said the suspect entered the school through a side entrance and went from the first floor to the second floor, firing multiple shots. It appears all the doors were locked and the suspect allegedly shot through a door, officials said.
The shooting was reported at 10:13 a.m. and the suspect was dead by 10:27 a.m., according to police. The officers who fatally shot the suspect were later identified by police as Rex Englebert, a four-year veteran of the force, and Michael Collazo, a nine-year veteran of the MNPD.
A car found near the school helped authorities identify the suspect, and authorities responded to the suspect's home, Drake said.
Police later announced that they seized "a sawed-off shotgun, a second shotgun and other evidence" from the home.
In a statement Monday night, the Covenant School said its community "is heartbroken."
"We are grieving tremendous loss and are in shock coming out of the terror that shattered our church and school," the statement read, in part. "We are focused on loving our students, our families, our faculty and staff and beginning the process of healing."
Throughout the day and afternoon, students were reunited with concerned parents. Families of the staff said they were shocked with the violence that had transpired.
Alex Apple told ABC News Live that his mother works at the school's front desk, and she was at her car when she got an alert saying to shelter in place.
"She got out of her car, heard the gunshots, so she fled," he said.
The school has about 209 students and about 40 to 50 staff members, officials said. Police said the school does not have a school resource officer.
President Joe Biden called the shooting "a family's worst nightmare."
The president once again urged Congress to pass an assault weapons ban, saying, "It's about time that we begin to make some more progress." Biden ordered flags at half-staff through Friday to honor the victims.
First lady Jill Biden said Monday, "I am truly without words. Our children deserve better."
Tennessee Gov. Bill Lee tweeted that he's "closely monitoring the tragic situation."
"Please join us in praying for the school, congregation & Nashville community," Lee said.
Nashville Mayor John Cooper thanked first responders for their swift action and called on Nashville residents to reach out and help one another.
"In this dark hour let us support each other," he said during a news conference.
Tennessee state Rep. Bo Mitchell spoke to Linsey Davis on ABC News Live Prime on Monday night, saying: "My two teenage boys leave, and with every expectation, I expect them to come home in the afternoon. We've got three parents tonight; their children did not get to come home today and it is sad."
Mitchell said he spent hours with students' parents on Monday, who wanted he and his colleagues to take action.
"Not a single parent asked me for a thought or a prayer," he said. "They asked for me and my colleagues to have some courage and do something about this."
Some parents took to social media in the wake of the Covenant School shooting to express their frustration of yet another mass shooting.
Kimberly Garcia, who lost her daughter, Amerie Jo Garza, in the Robb Elementary School shooting in Uvalde, Texas, tweeted, "When is enough going to be enough?"
"6 more innocent lives TAKEN? But it's not the guns right ? Wake up people," she wrote.
Lives Robbed, a group made up of some Uvalde victims' families advocating for changes in gun laws around the country, also tweeted their support for the Nashville families who lost loved ones Monday.
"We are with you. This is why we fight for change," the group tweeted.
ABC News' Alex Faul, Molly Nagle, James Hill and Ben Gittleson contributed to this report.