In the deadliest American school shooting since the massacre at Sandy Hook Elementary a decade ago, Salvador Ramos opened fire just before noon at Robb Elementary School in Uvalde, a small city west of San Antonio.
The 18-year-old killer, who had hinted about what he was going to do on social media, was shot and killed by a Border Patrol agent as he carried out his deadly rampage.
As the shock and horror reverberates across the nation, new details are emerging about the teenage killer who had slowly and quietly dropped out of school.
A former classmate, who asked not to be identified, told CNN he and Ramos were somewhat “close” and used to play Xbox together.
He said Ramos began showing up to class less and less as other kids bullied him about his clothing and his family's financial situation.
“He would, like, not go to school...and he just, like, slowly dropped out. He barely came to school,” the friend said.
The friend said they became even more distant from each other, but would occasionally message each other on Xbox.
Ramos got a job at a local Wendy's, where colleagues remembered him as quiet and antisocial.
Adrian Mendez, a night manager, said the gunman worked at the restaurant for a year and quit about a month ago.
He “went out of the way to keep by himself,” Mendez said. “You know how my guys talk to each other and are friendly? He wasn’t like that. No one really knew him.”
According to the New York Times, two parents who said they were friends of the gunman's family described him as serious and said he had a temper. One remembered he often talked back to his mother in his younger years.
The Washington Post quoted friends and relatives who described him as a lonely 18-year-old who "was bullied over a childhood speech impediment, suffered from a fraught home life and lashed out violently against peers and strangers recently and over the years".
Ramos reportedly dropped out of school after repeated bullying. "He missed long periods of high school, classmates said, and was not on track to graduate with them this year," a report said.
The Washington Post, quoting one of his friends, said, "About a year ago, Ramos posted on social media photos of automatic rifles that 'he would have on his wish list'...Four days ago, he posted images of two rifles he referred to as 'my gun pics'".
Several reports say Ramos had a disturbed home life and frequently argued with his mother.
The school shooter who had recently moved to Texas from North Dakota had reportedly bought two rifles on his 18th birthday and his social media was full of photos of his new guns.
Four days before Tuesday's shooting, Ramos reportedly sent his friend a picture of the AR and a backpack full of 5.56 rounds.
“[He had] probably like seven [magazines],” the friend said. “I was like: ‘Bro, why do you have this?" and he was like: ‘Don’t worry about it’.”
Ramos also told his friend that he “looked very different now”.
“You wouldn’t recognise me,” he messaged him less than a week ago.
Ramos also messaged a Los Angeles-based woman on May 12 on Instagram, tagging her in a photo of the guns.
“What your guns gotta do with me?,” she replied.
“I got a lil secret I wanna tell u,” he later messaged with a smiley face emoji covering its mouth.
She replied: "No it's just scary," adding: "I barely know you and you tag me in a picture with some guns?"
State police said Ramos shot and critically wounded his grandmother at her house, the address the gunman listed on his driver's license, before heading to the school.
Wearing body armour, he then walked into the Robb Elementary school carrying a handgun and a semiautomatic rifle and opened fire at the children. The shooter's motive remains unclear.
Ramos was then shot and killed after he had murdered 21 people.