Wrenching details have been steadily emerging since the tragedy, which also claimed the lives of two teachers.
Briefing reporters, Governor Greg Abbott revealed that teen shooter Salvador Ramos -- who was killed by police -- shot his 66-year-old grandmother in the face before heading to Robb Elementary School.
Ramos went on social media to share his plan to attack his grandmother -- who though gravely injured was able to alert the police.
He then messaged again to say his next target was a school, where he headed clad in body armor and wielding an AR-15 rifle.
'Pure evil'
Pressed on how the teen was able to obtain the murder weapon, the Texas governor repeatedly brushed aside suggestions that tougher gun laws were needed in his state -- where attachment to the right to bear arms runs deep.
"I consider this person to have been pure evil," Abbott said, articulating a position commonly held among US Republicans -- that unfettered access to weapons is not to blame for the country's gun violence epidemic.
Abbott's stance was echoed by the powerful National Rifle Association gun lobby, which issued a statement labeling the shooter as "a lone, deranged criminal."
But the governor was called out by a rival Democrat, who loudly interrupted the briefing to accuse him of deadly inaction.
"This is on you," heckled Beto O'Rourke, a fervent gun control advocate who is challenging Abbott for his job come November.
"You are doing nothing!" he charged. "This is totally predictable when you choose not to do anything."
O'Rourke's interruption came a day after President Joe Biden, in an emotional address, called on lawmakers to take on America's powerful gun lobby and enact tougher laws.
Biden announced Wednesday that he would soon visit Uvalde, as he renewed his plea for "common sense gun reforms."
"I think we all must be there for them. Everyone. And we must ask when in God's name will we do what needs to be done to, if not completely stop, fundamentally change the amount of the carnage that goes on in this country."
"I am sick and tired of what's going on and continues to go on," Biden said.
'Horror and pain'
In the shattered community of Uvalde, a small mainly Hispanic town about an hour from the Mexican border, there was outrage, too, at how such a tragedy could have occurred.
"I'm just heartbroken right now," said Ryan Ramirez, who lost his 10-year-old daughter Alithia in the rampage, as he and his wife Jessica attended a vigil at a local bull-riding arena together with some 1,000 other mourners.
"She was a real good artist" and aspired to greatness, Ramirez said, flipping through a portfolio of Alithia’s colorful paintings as well as birthday cards she drew for her mother.
Earlier in the day Rosie Buantel, a middle-aged local resident, told AFP: "I'm sad, and I'm angry at our government, for not doing more about gun control."
"We've gone through this one too many times. And still there's nothing done."
As broken families shared their news on social media, the names of the murdered children, most of Latino heritage, began coming out: they included Ellie Garcia, Jayce Carmelo Luevanos and Uziyah Garcia.
"My little love is now flying high with the angels above," Angel Garza, whose daughter Amerie Jo Garza had just celebrated her 10th birthday, posted on Facebook.
"I love you Amerie Jo," he wrote. "I will never be happy or complete again."
More than a dozen children were also wounded at the school, attended by more than 500 students aged around seven to 10 years old, most of them economically disadvantaged.
'Carnage'
Ramos' grandfather, 73-year-old Rolando Reyes -- whose wife still needed surgery after the attack -- voiced his pain for the bereaved families.
"I feel very sorry, and a lot of pain because a lot of those kids are grandkids of friends of mine," he told CBS News.
Details have emerged of Ramos as a deeply troubled teen -- he was repeatedly bullied over a speech impediment that included a stutter and a lisp and once cut up his own face "just for fun," a former friend, Santos Valdez, told The Washington Post.
In the days after turning 18 this month, Ramos purchased two assault rifles and several hundred rounds of ammunition, and a week later he staged his attack.
After driving his grandmother's vehicle to Robb Elementary, where he crashed it into a ditch, Ramos was confronted by a school resource officer -- but was able to enter through a back door and made his way to two adjoining classrooms.
"That's where the carnage began," said Steve McCraw, director of the Texas Department of Public Safety.
The Uvalde shooting was the deadliest since 20 elementary-age children and six staff were killed at the Sandy Hook school in Newtown, Connecticut in 2012.
According to the non-profit Gun Violence Archive, there have been more mass shootings -- in which four or more people were wounded or killed -- in 2022 than days so far this year.
Despite that, multiple attempts at national reform have failed in Congress.
