The Nashville school shooting that claimed the lives of six people, including three children, was planned months ahead of its execution, according to police.

NBC News reported that Nashville shooter Audrey Hale detailed plans to "commit mass murder at The Covenant Schools" in her journals that police found in her car and bedroom after the March 27 attack.

The Metropolitan Nashville Police Department earlier said that the Nashville shooter had carefully planned the attack, with detailed maps and surveillance.

Authorities have not yet released the possible motive for the mass shooting but stated that Hale "considered the actions of other mass murderers."

The police department said that the writings in the journals remain "under careful review by the MNPD," including the Federal Bureau Investigation's Behavioral Analysis Unit, which is based in Quantico, Virginia.

Officials said there might have been a sense of "resentment," which may have played a role in the attack.

The investigation of the Nashville school shooting is still ongoing.

READ NEXT: Uvalde Police Blasted as 'Cowards' After Nashville Cops Stopped School Mass Shooting in Minutes

Nashville Shooter Journals

Nashville police also clarified that Hale acted "totally alone" in executing the mass shooting in a private Christian school.

The Nashville shooter fired 152 rounds, most of which were 5.56 rifle rounds, and 26 were 9 mm rounds, according to CNN.

Hale was armed with three firearms and gained entry to the building by firing through the building's locked glass doors, as surveillance video showed.

Police said in a news release that writings left by Hale made it clear that the attack was "calculated and planned" and targeted the school and the Covenant Presbyterian Church, but the shots fired on the victims were random.

The Nashville school shooting creates a new wave of discussions of American gun violence, loose restrictions when it comes to access to firearms, and school safety.

Police said that Hale was under care for an emotional disorder. She legally purchased seven firearms and hid them at home, according to Nashville Police chief John Drake.

Nashville School Shooting

The Nashville shooter was killed within 14 minutes of the first 911 report of the shooting, according to police.

Nashville Mayor John Cooper said that the prompt police response likely "saved many lives," as reported by CBS News.

Responding police officers killed the shooter on the second floor of the building, with the shooter firing at police cars outside the school when officers engaged.

The three children killed were all nine years old and were identified as Evelyn Dieckhaus, Hallie Scruggs, and William Kinney.

Scruggs was the daughter of a pastor associated with the church affiliated with the school.

Meanwhile, the adults killed were the head of the school Katherine Koonce, 60; 61 years old Cynthia Peak, a teacher; and Mike Hill, the school's custodian.

A former student said that the head of the school was a "champion for all students" and "had a lot more to give."

READ MORE: Texas Police Shoot, Kill Gunman at Youth Summer Camp After He Opened Fire

This article is owned by Latin Post.

Written by: Mary Webber

WATCH: Covenant School Shooting: Suicide note, yearbooks, journals with ‘school shootings’ references found - from WKRN News 2