NASHVILLE, Tenn. -- The suspect in Monday's mass shooting at a small, private Christian school in Nashville, Tennessee, had legally purchased seven guns from five different local gun stores, and hid some of those weapons at home, police said Tuesday.
Three children and three adults were slain in the attack at The Covenant School. Nashville police on Tuesday released dramatic body camera footage from two officers who fired at the suspect, identified by police as 28-year-old Audrey Hale.
The video shows the officers entering the school, following the sound of the gunfire to the second floor and finding the suspect in a lobby area on the second floor.
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After an officer shouted "reloading," the video shows officers Rex Engelbert, a four-year veteran, and Michael Collazo, a nine-year veteran, firing at the suspect.
Hale was shot dead about 14 minutes after the initial 911 call came in, according to police.
The suspect was a former student, and while the Covenant School was likely targeted, Metropolitan Nashville Police Chief John Drake said it appears the "students were randomly targeted."
The suspect was armed with two assault-style rifles, a handgun and "significant ammunition," police said.
Hale, who lived in Nashville, had legally purchased seven guns from five different local gun stores, the chief told reporters Tuesday.
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Hale was under a "doctor's care for an emotional disorder," Drake said, and Hale's parents "were under the impression that was when she sold the one weapon" they believed Hale owned.
"As it turned out, she had been hiding several weapons within the house," Drake said.
Hale had a red bag when leaving home on Monday morning, Drake said. Hale's mother asked what was inside, but was "dismissed," according to Drake.
Hale's mother "didn't look in the bag, because at the time she didn't know that her daughter had any weapons," Drake said.
Hale allegedly shot through a locked door on the side of the school to gain entry, according to police. As authorities responded to the scene, the suspect fired on police cars from a second-floor window, police said.
The slain children were identified by police as Evelyn Dieckhaus, Hallie Scruggs and William Kinney, all 9 years old. The adult victims were identified as 61-year-old substitute teacher Cynthia Peak, 61-year-old custodian Mike Hill and 60-year-old Katherine Koonce, who was head of the school.
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The victims were found in different locations, Drake said. The custodian was struck when the shooter sprayed rounds at the glass door to enter, Drake said, and the head of school was found in the hallway.
Investigators searched Hale's home where they seized "a sawed-off shotgun, a second shotgun and other evidence," according to police.
"We do have writings and a book we consider to be like a manifesto," the police chief told ABC News' "Good Morning America" "We do have a map of the school, where it was diagramed how she would enter and how she might proceed to take on potential victims."
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"We have not been able to determine a motive as of yet," the chief said. "The investigation is very much still ongoing."
There is also "some speculation that the shooter did reach out to maybe a friend or some other people, but as of right now that's unconfirmed," Drake said.
"As soon as we know more, we'll continue to put the facts out there," he added.
The Covenant School, which teaches preschool through sixth grade, does not have a school resource officer, according to police. There are about 209 students and 40 to 50 staff members.
In a statement released 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 school said. "We are focused on loving our students, our families, our faculty and staff and beginning the process of healing."
"There's nothing more gut-wrenching than responding to a child," Nashville Fire Chief William Swann told ABC News' "GMA3." "That moment changes everything for you, because we all can relate to the innocence of it."
President Joe Biden on Tuesday called the shooting "absolutely heartbreaking" and "senseless."
"I never thought when I started my public life that guns would be the No. 1 killer of children in America," he said.
Biden said he had spoken with the police chief and "the two officers who went in and saved lives."
The president again called on Congress to ban assault weapons and said he wanted to "expose those people who will refuse to do something" to combat gun violence.
"I'm going to keep calling it out, remind people that they're not acting," he said. "They should act."
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White House press secretary Karine Jean-Pierre stressed that Congress must take action on gun legislation.
"What we need from congressional Republicans is courage," she told ABC News' "GMA3" on Tuesday. "What do you say to those parents? What do you say to those families? You can't say to them, 'There's nothing else that can be done.' That's not what their job is as legislators."
The "majority of Americans want common sense gun safety laws, they want to see [an] assault weapons ban. These are weapons of war," she said. "The president has done his part. We need Congress to do their part."
ABC News' Alex Faul, Matt Foster, James Hill, Doug Lantz, Molly Nagle, Darren Reynolds, John Santucci and Moe Zoyari contributed to this report. ABC Owned Television Stations and the Associated Press also contributed.