NASHVILLE: Nashville police worked Tuesday to pin down a motive behind a murderous rampage that saw three elementary school pupils and three staff shot dead by a heavily armed former student in a carefully planned and executed assault.
The shooter, who was killed by police, had prepared maps detailing surveillance and entry points at the school, and also left a written manifesto that suggested further attacks at other locations were planned.
Among the victims were an eight-year-old and two nine-year-olds, and two teachers, one of whom was the longtime head of the Covenant School, a small Christian academy for about 200 students.
Officials named the shooter as Audrey Hale, saying the 28-year-old was born female but identified as transgender.
In a chilling video released by Nashville police, Hale is seen shooting through a set of glass doors into the school, before stalking the empty halls with an assault rifle drawn as emergency alarm lights flash.
Armed with two assault rifles and a handgun, Hale, wearing a black military-style vest, camouflage pants and red baseball cap, advanced through the building, opening doors and walking through what appears to be the front desk area.
Police said at least two of the weapons were purchased legally, adding Hale had multiple rounds of ammunition and was "prepared for a confrontation with law enforcement."
Former schoolmate Averianna Patton told CNN of a message that Hale sent on Instagram on the morning of the shooting.
"One day this will make more sense," Hale wrote. "I've left behind more than enough evidence behind. But something bad is about to happen."
Patton said she called police to alert them at about the time the attack started.
In the search for a motive, Nashville police chief John Drake told NBC News that "there's some belief that there was some resentment for having to go to that school.
"She targeted random students in the school... whoever she came in contact with, she fired rounds," he added.
In a short phone interview with ABC News, Hale's mother, Norma Hale, said "It is very, very difficult right now... I think I lost my daughter today."
Officers were on the scene within about 15 minutes of the first emergency call at around 10 am (1500 GMT), engaging Hale, who returned fire before being shot dead.
Police later found material in the car that Hale drove to the scene.
Asked whether Hale's gender identity may have been a factor, police said they were investigating all leads.
As the country digested another mass shooting, mourners left flowers and stuffed toys at a growing makeshift memorial outside the school. Some kneeled in prayer.
Stacie Wilford, a nurse, told AFP it was "so scary" to have a shooting so close to home. She has an eight-year-old who attends a school only two miles down the road from Covenant.
"Whenever you hear about school shootings in other states, yes, you feel it, but when it's at your back door, it just sets in differently," Wilford said.
Chad Baker, 44, said he felt "horrified and very sad," adding that while he supports gun rights, there should be more regulation.
"There's just not enough to protect children," he told AFP.
"I carry a gun with me most days, but I don't need an assault rifle," he added. "And I don't think it should be as easy to buy flowers as it is a gun."
School shootings are alarmingly common in the United States, where the proliferation of firearms has soared in recent years.
President Joe Biden described the latest shooting as "sick" and said gun violence was "ripping the soul of this nation," as he urged Congress to pass a ban on the assault weapons often used in mass shootings.
The Covenant School was founded by and housed in the Covenant Presbyterian Church, part of a theologically conservative denomination, The New York Times reported.
One of the children who died in the shooting was Hallie Scruggs, the daughter of the church's pastor, Chad Scruggs.
Biden's calls for Congress to reinstate the national ban on assault rifles, which existed from 1994 to 2004, have run up against opposition from Republicans, who are staunch defenders of the constitutional right to bear arms and have a narrow majority in the House of Representatives.
The deadlock in Washington has come despite public uproar over high-profile massacres such as the one at Sandy Hook elementary school in Connecticut in 2012, when 26 people, including 20 children, were killed, and the 2018 murder of 17 people at a high school in Parkland, Florida.
There have been 129 mass shootings -- in which four or more people were shot or killed -- so far this year, according to the Gun Violence Archive. (AIR NEWS)