A heavily armed 28-year-old fatally shot three children and three adult staffers on Monday at a private Christian school the suspect once attended in Tennessee’s capital city before police killed the assailant, Reuters quoted authorities said.

The motive was not immediately known, but the suspect had drawn detailed maps of the school, including entry points for the building, and left behind a “manifesto” and other writings that investigators were examining, Police Chief John Drake told reporters.

The latest in an epidemic of deadly mass gun violence that has come to routinely terrorize even the most cherished of U.S. institutions unfolded on a warm spring morning at The Covenant School, whose students consist mostly of elementary school-age children, read the report.

Drake identified the suspect as Audrey Elizabeth Hale, 28, a resident of the Nashville area, and referred to the assailant by female pronouns. The chief said the suspect identified as transgender but provided no further clarity.

The Tennessean newspaper cited a police spokesperson as saying Hale used he/him pronouns. Hale used male pronouns on a LinkedIn page that listed recent jobs in graphic design and grocery delivery.

Police later released a school video showing the assailant blasting through glass doors with gunfire and roaming the halls, pointing a semi-automatic rifle. Hale wore a black vest over a white T-shirt, camouflage pants and a backwards red baseball cap in a video that showed only the shooter in the frame.

Addressing an early evening news conference, Drake said police were working on a theory about what may have precipitated the shooting and would “put that out as soon as we can.” He said the suspect had no known prior criminal history.

In a subsequent NBC News television interview, Drake said investigators believed the shooting stemmed from “some resentment” the suspect harbored “for having to go to that school” as a younger person.

The police chief did not specify the nature of such presumed resentment, or whether it had anything to do with the suspect’s gender identity or the Christian orientation of the school. Drake said the school was singled out for attack but the individual victims were targeted at random.

The Metropolitan Nashville Police Department began receiving calls at 10:13 a.m. of a shooter at the school, and arriving officers reported hearing gunfire coming from the building’s second floor, police spokesperson Don Aaron told reporters.

Two officers from a five-member team shot the assailant in a lobby area, and the suspect was pronounced dead by 10:27 a.m.

“The police department response was swift,” Aaron said.

Police said the suspect was armed with two assault-type guns and a 9 mm pistol, Reuters reported.

The victims were identified as Evelyn Dieckhaus, Hallie Scruggs, and William Kinney, all age 9, along with staffers Mike Hill, 61, a school custodian, Cynthia Peak, 61, a substitute teacher, and Katherine Koonce, 60, listed on the Covenant website as “head of school.”

Reacting in Washington to the latest school shooting, President Joe Biden urged the U.S. Congress again to pass tougher gun reform legislation, read the report.

“It’s sick,” Biden said, addressing the issue during an event at the White House and urging Congress again to pass a ban on assault-style weapons. “We have to do more to stop gun violence. It’s ripping our communities apart, ripping the soul of this nation.”

U.S. Senator Marsha Blackburn, a Tennessee Republican, said on Twitter that her office stands “ready to assist” those affected by the shooting.

But Rosanne Cash, daughter of the late Nashville country music star Johnny Cash and a singer-songwriter in her own right, responded by criticizing Blackburn’s ties to the National Rifle Association (NRA) gun lobby.

“You vote against every common sense gun control bill that comes across your desk, you’ve taken over $1 million from the NRA and you rank 14th in all Congress for NRA contributions. Spare us the hand-wringing,” Cash said on Twitter.

At the state level, Tennessee in 2021 did away with its permit requirement for carrying a concealed handgun and now allows anyone aged 21 and older to carry a firearm, either openly or concealed, without a permit, as long as they are legally allowed to purchase the weapon.

Possessing a handgun is outlawed in Tennessee for anybody who has been convicted of a felony offense involving violence or drugs, Reuters reported.

The Covenant School, founded in 2001, is a ministry of Covenant Presbyterian Church in the Green Hills neighborhood of Nashville with about 200 students, according to the school’s website. It serves preschool through sixth graders and held an active shooter training program in 2022, WTVF-TV reported.

Nashville Mayor John Cooper expressed sympathy for the victims and wrote on social media that his city “joined the dreaded, long list of communities to experience a school shooting.”

There have been 89 school shootings – defined as any incident in which a gun is discharged on school property – in the U.S. in 2023, according to the K-12 School Shooting Database, a website founded by researcher David Riedman. Last year saw 303 such incidents, the highest of any year in the database, which goes back to 1970.

NATO on Sunday criticized Vladimir Putin for what it called his “dangerous and irresponsible” nuclear rhetoric, a day after the Russian president said he would station tactical nuclear weapons in Belarus.

Putin announced the move on Saturday and likened it to the US stationing its weapons in Europe, while insisting that Russia would not violate its nuclear non-proliferation promises, Reuters reported.

Although the move was not unexpected, it is one of Russia’s most pronounced nuclear signals since the beginning of its invasion of Ukraine 13 months ago, and Ukraine called for a meeting of the UN Security Council in response.

While Washington, the world’s other nuclear superpower, played down concerns about Putin’s announcement, NATO said the Russian president’s non-proliferation pledge and his description of US weapons deployment overseas were way off the mark.

“Russia’s reference to NATO’s nuclear sharing is totally misleading. NATO allies act with full respect of their international commitments,” a NATO spokesperson said in emailed comments to Reuters on Sunday.

“Russia has consistently broken its arms control commitments, most recently suspending its participation in the New START Treaty,” the unnamed spokesperson said.

New START caps the number of strategic nuclear warheads that the United States and Russia can deploy, and the deployment of land and submarine-based missiles and bombers to deliver them.

A top security adviser to Ukrainian President Volodymyr Zelenskiy, Oleksiy Danilov, said Russia’s plan would also destabilize Belarus, which he said had been taken “hostage” by Moscow.

Experts said Russia’s move was significant since it had until now been proud that unlike the United States, it did not deploy nuclear weapons outside its borders. It may be the first time since the mid-1990s that it has done so, Reuters reported.

Another senior Zelenskiy adviser on Sunday scoffed at Putin’s plan, saying the Russian leader is “too predictable”.

“Making a statement about tactical nuclear weapons in Belarus, he admits that he is afraid of losing and all he can do is scare with tactics,” Mykhailo Podolyak wrote on Twitter.

Washington appeared to see no change in the potential for Moscow to use nuclear weapons in the war in Ukraine, and it and NATO said the news would not affect their own nuclear position.

“We have not seen any changes in Russia’s nuclear posture that would lead us to adjust our own,” the NATO spokesperson wrote.

Facing a potential indictment, Donald Trump took a defiant stance at a rally Saturday in Waco, Texas, disparaging the prosecutors investigating him and predicting his vindication as he rallied supporters in a city made famous by deadly resistance against law enforcement.

With a hand over his heart, Trump stood at attention when his rally opened with a song called “Justice for All” performed by a choir of people imprisoned for their roles in the Jan. 6 insurrection at the U.S. Capitol. Some footage from the insurrection was shown on big screens displayed at the rally site as the choir sang the national anthem and a recording played of Trump reciting the Pledge of Allegiance, Associated Press reported.

The extraordinary display opened Trump’s first rally of his 2024 Republican presidential campaign. He then launched into a speech brimming with resentments and framed the probes, including a New York grand jury investigation, as political attacks on him and his followers.

“You will be vindicated and proud,” Trump said. “The thugs and criminals who are corrupting our justice system will be defeated, discredited and totally disgraced.”

Trump’s event at the airport grounds in Waco was part of a broader effort by the former president to use the potential indictment as a rallying cry for supporters to maintain his status as the GOP frontrunner in what is expected to be a crowded primary. It came one day after Trump raised the specter of violence should he become the first former president in U.S. history to face criminal charges.

Trump declared Saturday that his “enemies are desperate to stop us” and that “our opponents have done everything they can to crush our spirit and to break our will.”

He added: “But they failed. They’ve only made us stronger. And 2024 is the final battle, it’s going to be the big one. You put me back in the White House, their reign will be over and America will be a free nation once again.”