A gunwoman wielding two “assault-style” rifles and a pistol killed three pupils and three adults at a private Christian school in Nashville, Tennessee, on Monday, in the latest in a series of mass shootings in a country growing increasingly unnerved by bloodshed in schools.

The gunwoman died after being shot by police following the violence at The Covenant School, a Presbyterian school for about 200 pupils.

She had drawn a detailed map of the school, including potential entry points, and carried out surveillance before the attack, police said.

The victims were identified as Evelyn Dieckhaus, Hallie Scruggs and William Kinney, all aged nine, and Cynthia Peak, 61, Katherine Koonce, 60, and Mike Hill, 61.

The school website lists Ms Koonce as the headteacher.

Police said the gunwoman was 28 and from Nashville, after initially saying she appeared to be in her teens.

She is believed to have been a former pupil at the school.

The killings come as communities around the country reel from a spate of school violence, including the massacre at a primary school in Uvalde, Texas, last year, a pupil who shot his teacher in Virginia, and a shooting last week in Denver that wounded two administrators.

President Joe Biden called on Congress again to pass his assault weapons ban in the wake of the Nashville shooting.

Nashville School Shooting
Police and FBI investigate a house in Nashville after the mass shooting (Andrew Nelles/The Tennessean/AP)

“It’s heartbreaking, a family’s worst nightmare,” he said. “It’s ripping at the soul of this nation, ripping at the very soul of this nation.”

First lady Jill Biden said: “I am truly without words, and our children deserve better. We stand, all of us, we stand with Nashville in prayer.”

The suspect’s identity as a woman surprised experts on mass shootings.

Women make up only about 5% to 8% 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 such individuals.

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 gunmen were males who killed four or more people within a 24-hour time frame at schools with pupils from nursery age to 18.

The tragedy unfolded over roughly 14 minutes. Police received an initial call about an active gunman at 10.13am.

Officers began clearing the ground floor of the school when they heard gunshots coming from the next floor, police spokesman Don Aaron said.

Two officers from a five-member team opened fire in response, fatally shooting the suspect at 10.27am, Mr Aaron said.

He 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.

The victims were pronounced dead on arrival at the Monroe Carell Junior Children’s Hospital, said Craig Boerner, a spokesman for Vanderbilt University Medical Centre, which is affiliated with the children’s hospital.

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

Police with rifles, heavy vests and helmets could be seen walking through the school car park and around the grassy perimeter of the building.

Helicopter footage from WTVF also showed the officers looking around a wooded area between the campus and a nearby road.

Nashville School Shooting
Children are led away from the school (Jonathan Mattise/AP)

Jozen Reodica heard the police sirens and fire engines 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.”

On WTVF TV, reporter Hannah McDonald said that her mother-in-law works at the front desk at The Covenant School. The woman had stepped outside for a break and was coming back when she heard gunshots, Ms McDonald said during a live broadcast.

The reporter said she has not been able to speak to her mother-in-law but said her husband had.

Nashville School Shooting
A child is reunited with his parents (John Bazemore/AP)

“In a tragic morning, Nashville joined the dreaded, long list of communities to experience a school shooting,” Nashville mayor John Cooper tweeted, thanking emergency services and medical professionals.

“My heart goes out to the families of the victims. Our entire city stands with you.”

The Covenant School was founded as a ministry of Covenant Presbyterian Church in 2001, according to the school’s website.

The school is in the affluent Green Hill neighbourhood just south of Nashville, close to the city’s top universities and home to the famed Bluebird Cafe – a beloved spot for musicians and song writers.

The school has 33 teachers, the website said. The school’s website features the motto Shepherding Hearts, Empowering Minds, Celebrating Childhood.

Democratic state representative Bob Freeman, whose district includes The Covenant School, called Monday’s shooting an “unimaginable tragedy”.

“I live around the corner from Covenant and pass by it often. I have friends who attend both church and school there,” Mr Freeman said in a statement.

“I have also visited the church in the past. It tears my heart apart to see this.”