FILE - A balloon with names of the victims is seen at a memorial at the entrance to The Covenant School on Wednesday, March 29, 2023, in Nashville, Tenn. Bipartisan gun legislation signed by President Biden in 2022 has already prevented some potentially dangerous people from owning guns. But Democrats are calling for more action after mass shootings in Nashville and elsewhere, and Congress is at a familiar impasse. Associated Press

Wade Payne

NASHVILLE, Tenn. — As students across Nashville walked out of class on Monday to protest gun violence at the Tennessee Capitol following a school shooting last week, police said the person who killed six people, including three 9-year-old children, had been planning the massacre for months.

Police have not established a motive for the shootings at The Covenant School, a small Christian elementary school where the 28-year-old shooter was once a student, according to a Monday news release from the Metropolitan Nashville Police Department. Both Nashville police and FBI agents continue to review writings left behind by Audrey Hale, both in Hale's vehicle and home, police said.

“It is known that Hale considered the actions of other mass murderers,” police said.

The three children who were killed in the shooting were Evelyn Dieckhaus, Hallie Scruggs and William Kinney. The three adults were Katherine Koonce, 60, the head of the school, custodian Mike Hill, 61, and 61-year-old substitute teacher Cynthia Peak.

Hale fired a total of 152 rounds during the attack before being killed by police. That included 126 rifle rounds and 26 nine-millimeter rounds, according to police.

Meanwhile, Tennessee Gov. Bill Lee on Monday unveiled a proposal to allocate enough funding to place a school resource officer in every public school, as well as increase school building security and boost mental health resources. The announcement marks the first public address the Republican governor has made since last week’s shooting in Nashville.

Police have said Hale was under a doctor’s care for an undisclosed “emotional disorder.” However, authorities haven’t disclosed a link between that care and the shooting. Police also said Hale was not on their radar before the attack.

Social media accounts and other sources indicate that the shooter identified as a man and might have recently begun using the first name Aiden. Police have said Hale “was assigned female at birth” but used masculine pronouns on a social media profile. However, police have continued to use female pronouns and the name Audrey to describe Hale.