• Audrey Hale, a former student at Covenant School, fired 152 rounds during the Nashville mass shooting on March 27
• The motive remains unknown, but detectives found that Hale considered the actions of previous mass murderers
• The Nashville school shooting suspect possessed a detailed map of the school and "writings and a manifesto-like book"

The 28-year-old shooter who killed three children and three adults at a Christian school in Nashville last week fired 152 rounds, police in Nashville said on Monday, adding that while they have yet to determine a motive, the shooter planned the attack "over months" and studied other mass murderers.

The shooter, identified as former student Audrey Hale, "acted completely alone," according to a Monday Metro Nashville Police report.

Nashville School Shooting Suspect's Motive

Detectives from the police department and the FBI's Behavioral Analysis Unit continue to examine Hale's papers, which, according to authorities on Monday, show evidence of her plotting.

The majority of Hale's shots, 126, were 5.56 rifle ammunition, while 26 were 9 mm rounds, according to authorities. The investigation update on Monday comes a week after Hale - armed with three firearms, according to police - attacked the Covenant School, blasting through the building's secured glass doors to gain admission.

According to police, Hale was "shooting through a window at arriving police cars" when Nashville officers arrived on the site and engaged him within minutes.

A spokesperson for the Nashville police department, said Hale was shot and killed by two officers at 10:27 a.m., 14 minutes after the shooter entered the building, as documented by bodycam footage later provided by police.

On Monday, Officer Rex Engelbert shot four 5.56 bullets from his rifle, while Officer Michael Collazo fired four rounds from his 9 mm pistol, CNN reported. Nine-year-olds Evelyn Dieckhaus, William Kinney, and Hallie Scruggs were killed in the massacre, along with a 61-year-old school custodian, a 61-year-old substitute teacher, and the 60-year-old principal of the school.

Nine-year-olds Evelyn Dieckhaus, William Kinney, and Hallie Scruggs were slain in the massacre, along with a 61-year-old school custodian, a 60-year-old substitute teacher, and the school's 60-year-old principal, Katherine Koonce.

While authorities continue to investigate the attack's purpose, they have stated in a press release that Hale's writings indicate that it was "considered and planned."

According to authorities, Hale targeted the school and the Covenant Presbyterian Church, which is attached to the school, although it is thought that the victims were shot at random. The school massacre - the deadliest since May, when 21 people, including 19 children, were slain at a school in Uvalde, Texas - reignited arguments over the epidemic of American gun violence, access to firearms, and school safety.

Hale, who authorities claimed was receiving treatment for an emotional disorder, had lawfully purchased and concealed seven weapons, according to Metropolitan Nashville Police Chief John Drake.

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Audrey Hale Plot Massive Shooting

According to Fox News, police claimed that while they were still examining Hale's possible motive, the killer "took into account the deeds of past mass murderers" when planning the slaughter. In addition to a manifesto, authorities say they found artwork connected to the attack, detailed blueprints of the school, and maps depicting potential entrance sites for the killing.

Although Hale fired hundreds of rounds into the school and through the window toward responding officers, two heroic officers fired four rounds each. Officer Rex Engelbert was the first to open fire after he rounded a curve and spotted the suspect standing near a huge second-story window, where police claim he was shooting at further officers who were still outside the school.

Per WBAL, Hale was shot and killed inside the school by police. Last week, Metropolitan Nashville Police Chief John Drake said that Hale had a detailed map of the school as well as "writings and a book we regard to be a manifesto."

Hale's writings, which were discovered in a car at the crime scene in a bedroom, are being reviewed by Nashville police and the FBI, according to a Monday statement. A police spokessperson stated that Hale was assigned female at birth, but pointed to a Hale-affiliated social media account that featured the pronouns he/him.

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