Editor's note: This story contains graphic descriptions of violence.
(CNN) -- The Metro Nashville Police Department released body-camera footage Tuesday from the two officers who rushed into the Covenant School on Monday and fatally shot the mass shooter.
The footage is from the body-worn cameras of officers Rex Engelbert and Michael Collazo, who police said fatally shot the attacker on Monday at 10:27 a.m. The videos show a group of five officers entered the school amid wailing fire alarms and immediately went into several rooms to look for the suspect.
They heard gunfire on the second floor and so hustled up the stairs as the bangs grew louder, the video shows. The officers approached the sound of gunfire and Engelbert, armed with an assault-style rifle, rounded a corner and fired multiple times at a person near a large window, who dropped to the ground, the video shows.
Collazo then pushed forward and appeared to shoot the person on the ground four times with a handgun, yelling "Stop moving!" The officers finally approached the person, moved a gun away and then radioed "Suspect down! Suspect down!"
The video release comes as police in Nashville are digging into the background and motivations of the shooter, a 28-year-old former Covenant student named Audrey Hale who officials said carefully planned the attack.
The attack was the 19th shooting at an American school or university in 2023 in which at least one person was wounded, according to a CNN tally, and the deadliest since the May attack in Uvalde, Texas, left 21 dead. There have been 42 K-12 school shootings since Uvalde.
Six people were killed in the Covenant School, a private Christian school educating about 200 students from Pre-K through 6th grade. The school is a ministry of Covenant Presbyterian Church, its website states.
The victims included three 9-year-old students: Evelyn Dieckhaus, William Kinney and Hallie Scruggs, the daughter of lead church pastor Chad Scruggs. Also killed were Cynthia Peak, 61, believed to be a substitute teacher; Katherine Koonce, the 60-year-old head of the school; and Mike Hill, a 61-year-old custodian, police said.
Nashville Mayor John Cooper told CNN the swift police response prevented further disaster.
"It could have been worse without this great response," the mayor of the police response. "This was very planned and numerous sites were investigated."
He said he expected the body camera footage and more of the shooter's writings to be released on Tuesday.
"They found a lot of documents. This was clearly planned," he said. "There was a lot of ammunition. There were guns."
Shooter had maps of the school
Police said the shooting was targeted, closely planned and outlined in documents from the shooter.
Hale left writings pertaining to the shooting and had scouted a second possible attack location in Nashville, "but because of a threat assessment by the suspect -- there's too much security -- decided not to," Metro Nashville Police Chief John Drake said.
The shooter left behind "drawn out" maps of the school detailing "how this was all going to take place," he added.
The writings revealed the attack at the Christian school "was calculated and planned," police said. The shooter was "someone that had multiple rounds of ammunition, prepared for confrontation with law enforcement, prepared to do more harm than was actually done," Drake said.
Three weapons -- an AR-15, a Kel-Tec SUB 2000, and a handgun -- were found, and police believe Hale got at least two of the weapons legally, he said. A search warrant executed at Hale's home led to the seizure of a sawed-off shotgun, a second shotgun and other evidence, according to police.
Police have referred to Hale as a "female shooter," and at an evening news conference added Hale was transgender. Hale used male pronouns on a social media profile, a spokesperson told CNN when asked to clarify.
Hale graduated from Nossi College of Art & Design in Nashville last year, the president of the school confirmed to CNN, and worked as a freelance graphic designer and a part-time grocery shopper, a LinkedIn profile says.
How the shooting unfolded
Information from police and from the shooter's childhood friend helped illuminate a timeline of the deadly attack.
Just before 10 a.m. Monday, the shooter sent an ominous message to a childhood friend, the friend told CNN on Tuesday. In an Instagram message to Averianna Patton, a Nashville radio host, just before 10 a.m. Monday, the shooter said "I'm planning to die today" and that it would be on the news.
"One day this will make more sense," Hale wrote. "I've left more than enough evidence behind. But something bad is about to happen."
Patton told CNN's Don Lemon she was the shooter's childhood basketball teammate and "knew her well when we were kids" but hadn't spoken in years and is unsure why she received the message. Disturbed by its content, she called a suicide prevention line and the Nashville Davidson County Sheriff's Office at 10:13 a.m.
At that very minute, police in Nashville also got a 911 call of an active shooter inside Covenant School and rushed there.
Armed with three firearms, the shooter got into the school by firing through glass doors and climbing through to get inside, surveillance video released by Metro Nashville Police shows. Pointing an assault-style weapon, the shooter walked through the school's hallways, the video shows.
As the first five officers arrived, they heard gunfire from the second floor. The shooter was "firing through a window at arriving police cars," police said in the news release.
Police went upstairs, where two officers opened fire, killing the shooter at 10:27 a.m., police spokesperson Don Aaron said.
After the shooter was dead, children were evacuated from the school and taken in buses to be reunited with their families. They held hands and walked in a line out of the school, where community members embraced, video showed.
"This school prepared for this with active shooter training for a reason," Nashville Metropolitan Councilman Russ Pulley told CNN. "We don't like to think that this is ever going to happen to us. But experience has taught us that we need to be prepared because in this day and time it is the reality of where we are."
Patton, meanwhile, had "called Nashville's non-emergency line at 10:14 a.m. and was on hold for nearly seven minutes before speaking with someone who said that they would send an officer to my home," she told CNN affiliate WTVF, but by then the shooting was already underway.
"An officer did not come to my home until 3:29 p.m.," Patton said.
Later, Nashville's police chief commended the five officers for their quick response.
"I was hoping this day would never ever come here in the city. But we will never wait to make entry and to go in and to stop a threat especially when it deals with our children," Drake said in a Monday news conference.
The swift response marked a stark contrast with the delay of more than an hour by law enforcement in Uvalde before that shooter was confronted and killed -- a lag that revived a nationwide conversation about use of force during shootings in public places, especially schools.
Three children and three adults were killed
Two Covenant School employees are among the victims of Monday's mass shooting, according to the school.
Katherine Koonce was identified as the head of the school, its website says. She attended Vanderbilt University and Trevecca Nazarene University in Nashville and got her master's degree from Georgia State University.
Mike Hill was identified in the staff section of the Covenant Presbyterian Church's website as facilities/kitchen staff. Hill, 61, was a custodian at the school, per police. A friend confirmed his image to CNN.
Cynthia Peak, 61, was believed to be a substitute teacher, police said Monday.
The Covenant School issued a statement Monday night grieving the shooting.
"Our community is heartbroken. We are grieving tremendous loss and are in shock coming out of the terror that shattered our school and church. We are focused on loving our students, our families, our faculty and staff and beginning the process of healing," the school said in a statement.
"Law enforcement is conducting its investigation, and while we understand there is a lot of interest and there will be a lot of discussion about and speculation surrounding what happened, we will continue to prioritize the well-being of our community.
"We appreciate the outpouring of support we have received, and we are tremendously grateful to the first responders who acted quickly to protect our students, faculty and staff. We ask for privacy as our community grapples with this terrible tragedy -- for our students, parents, faculty and staff," the statement said.
Cooper, the Nashville mayor, said he is "overwhelmed at the thought of the loss of these families, of the future lost by these children and their families."
"The leading cause of kids' death now is guns and gunfire and that is unacceptable," Cooper said.
A recent study published in the journal JAMA Pediatrics in December backs that point, finding that homicide is a leading cause of death for children in the United States and the overall rate has increased an average of 4.3% each year for nearly a decade.
President Joe Biden called the shooting "heartbreaking, a family's worst nightmare," while advocating for gun reform.
Biden said Congress needs to pass an assault weapons ban because we "need to do more to protect our schools." However, a bipartisan solution is extremely unlikely this Congress with a slim Democratic majority in the Senate and a GOP-led House.