The suspect in a Nashville, USA school shooting on Monday had drawn a detailed map of the school, including potential entry points, and done surveillance before killing three students and three adults.

It’s the latest in a series of mass shootings, in a country growing increasingly unnerved by bloodshed in schools.

The suspect, who was killed by police, is believed to be a former student at The Covenant School in Nashville, where the shooting took place.

Children from The Covenant School, a private Christian school in Nashville, Tennessee, hold hands as they are taken to a reunification site. Photo / AP

Police initially identified the shooter as a teenage girl, but have since said the 28-year-old shooter identified as transgender.

The victims were identified as Evelyn Dieckhaus, Hallie Scruggs, and William Kinney, all 8 or 9 years old, and adults Cynthia Peak, 61, Katherine Koonce, 60, and Mike Hill, 61.

The website of The Covenant School, a Presbyterian school founded in 2001, lists a Katherine Koonce as the head of the school. Her LinkedIn profile says she has led the school since July 2016.

A group prays with a child outside the reunification centre at the Woodmont Baptist Church. Photo / AP

The attack at The Covenant School - which has about 200 students from preschool through to sixth grade, as well as roughly 50 staff members - comes as communities around the nation are reeling from a spate of school violence, including the massacre at an elementary school in Uvalde, Texas, last year; a first-grader who shot his teacher in Virginia; and a shooting last week in Denver that wounded two administrators.

“I was literally moved to tears to see this and the kids as they were being ushered out of the building,” Metropolitan Nashville Police Chief John Drake said at an afternoon news conference.

The suspect’s identity and motive have not been released.

The Covenant School was founded as a ministry of Covenant Presbyterian Church. The affluent Green Hills neighbourhood, just south of downtown Nashville, where the Covenant School is located, is home to the famed Bluebird Café - a beloved spot for musicians and songwriters.

Salvador Ramos from Ulvades, Texas was identified as the shooter at a school in May 2022 in which 14 kids and a teacher died. Photo / @salv8dor_

President Joe Biden, speaking at an unrelated event at the White House on Monday, called the shooting a “family’s worst nightmare” and implored Congress again to pass a ban on certain semi-automatic weapons.

“It’s ripping at the soul of this nation, ripping at the very soul of this nation,” Biden said.

The suspect’s identity as a woman surprised experts on mass shootings. Female shooters make up only about 5 per cent to 8 per cent of all mass shooters, said Adam Lankford, a criminal justice professor at the University of Alabama who has closely studied the psychology and behaviour of mass shooters.

Photo / AP

There have been seven mass killings at US schools since 2006, according to a database maintained by The Associated Press and USA Today in partnership with Northeastern University. In all of them, the shooters were males who killed four or more people within a 24-hour timeframe.

Researchers believe there are three main explanations for why men commit more shootings than women, according to Jonathan Metzl, a professor of sociology and psychiatry at Vanderbilt University who has studied mass shootings for more than a decade.

Metzl listed those explanations as: men have more testosterone, are socialised to be engaged in violence, and own more guns than women.

“From school shootings historically, very often we think that people have some historical connection or emotional connection to the school,” he said, calling the Nashville shooting “an untold story”.

Monday’s tragedy unfolded over roughly 14 minutes. Police received the initial call about an active shooter at 10.13 am.

Officers at an active shooter event that took place at Covenant School, Covenant Presbyterian Church, in Nashville, Tennessee. Photo / Nashville Police Department, AP

Officers began clearing the first story of the school when they heard gunshots coming from the second level, police spokesperson Don Aaron said during a news briefing.

Two officers from a five-member team opened fire in response, fatally shooting the suspect at 10.27 am, Aaron said. One officer had a hand wound from cut glass.

Aaron said there were no police officers present or assigned to the school at the time of the shooting because it is a church-run school.

Other students walked to safety, holding hands as they left their school, surrounded by police cars, to a nearby church to be reunited with their parents.

A man walks with children at the Woodmont Baptist Church. Photo / AP

Rachel Dibble, who was at the church as families found their children, described the scene as everyone being in “complete shock.”

“People were involuntarily trembling,” said Dibble, whose children attend a different private school in Nashville. “The children... started their morning in their cute little uniforms, they probably had some Froot Loops and now their whole lives changed today.”

Dr Shamendar Talwar, a social psychologist from the United Kingdom who is working on an unrelated mental health project in Nashville, raced to the church as soon as he heard the news of the shooting, to offer help. He said he was one of several chaplains, psychologists, life coaches and clergy inside supporting the families.

“All you can show is that the human spirit that basically that we are all here together... and hold their hand more than anything else,” Talwar said.

Jozen Reodica heard the police sirens and fire trucks blaring from outside her office building nearby. As her building was placed under lockdown, she took out her phone and recorded the chaos.

“I thought I would just see this on TV,” she said. “And right now, it’s real.”

Top legislative leaders announced Monday that the GOP-dominant State house would meet briefly later in the evening and delay taking up any legislation.

“In a tragic morning, Nashville joined the dreaded, long list of communities to experience a school shooting,” Mayor John Cooper wrote on Twitter.

Nashville has seen its share of mass violence in recent years, including a Christmas Day 2020 attack where a recreational vehicle was intentionally detonated in the heart of Music City’s historic downtown, killing the bomber, injuring three others and forcing more than 60 businesses to close.