Mr Pulley said the head of the school “immediately ended” the Zoom meeting and headed in the direction of the shooter.

“It is my understanding from a witness at the school that Katherine Koonce was on a Zoom call when she heard the first shot,” Mr Pulley said.

“She immediately ended the call, got up and headed straight for the shooter.”

Ms Koonce’s body was found in a hallway of the school, according to Nashville Police Chief John Drake.

He could not confirm the exact instances leading up to her death.

“There was a confrontation, I’m sure – you can tell the way she was lying in the hallway,” Chief Drake said, adding that she had been “assassinated”.

Prior to Monday’s shooting, Ms Koonce had already taken many efforts in her school to better protect students from gun violence, including seeking advanced-level active-shooter training.

Mr Pulley said she had “protected her children”. ​

​Parents with students at the school also praised Ms Koonce, with one describing her as a “saint”.

“She did so much for those kids,” the mother of two of the school’s children said.

“She knew every single student by name,” she said. “She did everything to help them when families couldn’t afford things, it didn’t matter. She found ways for them to stay.”

Two other staff members were also killed in the shooting. They were identified as Cynthia Peak and Mike Hill, both aged 61.

Three students – Evelyn Dieckhaus, Hallie Scruggs and William Kinney, all aged nine – also died in the attack.

The shooting unfolded just after 10am on Monday when shooter Audrey Hale drove to the elementary school heavily armed.

Hale – a 28-year-old former student at the Christian school – broke into the school building by shooting through the glass side doors and climbing inside.

The killer then stalked the corridors, shooting the six victims.

Responding officers fatally shot the assailant at 10.27am – 14 minutes after the first 911 call reporting an active shooter came in at 10.13am.

Minutes before the shooting, Hale had sent some chilling final messages to a friend warning that “something bad is about to happen”.

Nashville police revealed on Tuesday that Hale legally bought seven firearms in the run-up to the mass shooting – despite receiving mental health treatment at the time.

In a press conference, Chief Drake said Hale had been under medical care “for an emotional disorder” and that family members “felt that she should not own weapons”.

Police have identified the shooter by name at birth – Hale reportedly was a transgender man who used he/him pronouns, though law enforcement officials initially described the shooter as a woman.

He added that Hale’s parents were aware the suspect had purchased one firearm but believed it had since been sold.

Even if Hale’s parents had been aware of the stash of weapons and contacted law enforcement, there is no red flag law in Tennessee that could have been used to take away the firearms. ​

Investigators are still working to determine the motive for the attack, which was both planned and targeted.

Hale left behind a manifesto and a detailed map of the building.

Police said they also found evidence suggesting plans for other attacks, including on a local mall and targeting family members. 

Hale – an illustrator and graphic designer who attended Nossi College of Art – had no criminal record prior to Monday’s massacre.