The shooting happened on Monday at The Covenant School, a private Presbyterian school for about 200 students from preschool through sixth grade.
All three children had gunshot wounds, officials said, and they were pronounced dead upon arrival at the Monroe Carell Jr Children’s Hospital at Vanderbilt.
No further details were immediately released on their ages or their identities, or the identities of the adults who were killed.
The Metropolitan Nashville Police Department said on Monday that the suspect was dead after being “engaged by officers”.
Police later said the shooter was a woman who “appeared to be in her teens”, but that they were still working to identify her. Police said she had “at least” two assault rifles and a handgun. A motive was not immediately clear.
Students could be seen being walked to safety after the incident, holding hands as they left their school surrounded by police cars. They were brought to a nearby church to be reunited with their parents.
Helicopter footage from the WTVF local news station showed police officers looking around a wooded area between the campus and a nearby road.
Jozen Reodica said she heard the police sirens and fire trucks blaring from outside her office building nearby. As the building was placed under lockdown, she took out her phone and recorded the chaos.
“I thought I would just see this on TV,” she told The Associated Press news agency. “And right now, it’s real.”
Attacks at US schools have become relatively common, including a massacre last year at a primary school in Uvalde, Texas that left 19 young students and two teachers dead.
In February, a gunman killed three students and wounded five others in an attack on the campus of Michigan State University in East Lansing, Michigan.
As of Monday, there had been at least 128 mass shootings in the US in 2023, according to the Gun Violence Archive, a group that defines a mass shooting as an incident involving four or more victims.
Since 2020, the number of mass shootings every year in the US has hovered above 600, with 646 recorded in 2022, according to the Gun Violence Archive database.
Meanwhile, a Federal Bureau of Investigation (FBI) report recorded a 61 percent jump in so-called “active shooter” incidents in the country in 2021 compared to the previous year.
The department defines an “active shooter” as someone engaged in killing or attempting to kill people in a public space in a seemingly random fashion.
About one in five “active shooter” incidents in 2021 were also mass killings.
