At least 19 children and two teachers were killed after a gunman opened fire at Robb Elementary School in Uvalde, west of San Antonio, according to the Texas Department of Public Safety.
The alleged gunman -- identified by officials as 18-year-old Salvador Ramos, a student at Uvalde High School -- is dead, authorities said.
Ramos turned 18 on May 16. Multiple law enforcement officials told ABC News he purchased two AR-15-style rifles on May 22, two days before the massacre and six days after his birthday. They were legal purchases.
Once the shooter made entry into a classroom he barricaded himself and opened fire, according to the sources.
Officers from the Uvalde Police Department and agents from Customs and Border Protection entered into the classroom and immediately took fire from the gunman before they shot and killed him.
Investigators are going through the ballistics to determine who fired the fatal shot.
"When parents drop their kids off at school, they have every expectation to know that they're going to be able to pick their child up when that school day ends. And there are families who are in mourning right now," Gov. Greg Abbott told reporters.
Here's what we know about the victims so far.
Amerie jo Garza, 10
Amerie jo Garza's father, Angel Garza, told ABC News that his daughter just turned 10 two weeks ago -- her birthday was May 10. Garza met with U.S. Marshals Tuesday night, who informed him that his daughter had been killed in the shooting at her elementary school.
"Thank you everyone for the prayers and help trying to find my baby," Garza wrote in a statement to ABC News. "She's been found. My little love is now flying high with the angels above. Please don't take a second for granted. Hug your family. Tell them you love them. I love you Amerie jo. Watch over your baby brother for me."
Xavier Lopez, 10
Fourth-grader Xavier Lopez died in Tuesday's elementary school shooting, his family confirmed to ABC News.
According to his cousin, Xavier's mom was at his awards ceremony one to two hours prior to the shooting, not knowing it would be the last time she would see him.
Eva Mireles, a fourth-grade teacher at the elementary school, was killed in the shooting, her aunt, Lydia Martinez Delgado, confirmed to ABC News. She had been a teacher in the school district for approximately 17 years, Delgado said.
"I'm furious that these shooting continue. These children are innocent. Rifles should not be easily available to all," Delgado said. "This is my hometown, a small community of less than 20,000. I never imagined this would happen, especially to loved ones."
"All we can do is pray hard for our country, state, schools and especially the families of all," she said.
Eliahana Cruz Torres, 10
Eliahana Cruz Torres died in the Tuesday shooting, her grandfather Adolfo Cruz confirmed to ABC News. It was confirmed to the family late Tuesday night.
Annabelle Rodriguez, 10 and Jackie Cazares, 10
Aunt Polly Flores identified her two nieces Annabelle Rodriguez, 10 and Jackie Cazares, 10 as among the students killed in the Uvalde shooting. They were both in the fourth grade, in the same class at Robb Elementary, she told ABC News.
Rojelio Torres, 10
Rojelio Torres' mother confirmed to ABC News her son was confirmed dead in the shooting. She described Rojelio as a "very smart and loving child."
Jayce Carmelo Luevanos, 10, and Jailah Nicole Silguero, 11
Cousins Jayce Luevanos and Jailah Silguero were identified as victims on Wednesday.
"They were nothing but loving baby angels, always had a smile on their face just full of life," their cousin said in a statement to ABC News. "I can't believe this happened to our angels."
Irma Garcia, a fourth-grade teacher at the elementary school, was identified as a victim on Wednesday, her family confirmed to ABC News. She had been a teacher at the school for 23 years.
Her family said she and her husband, Joe, were about to celebrate their 25th wedding anniversary. The two had known each other since eighth grade and have four children together.
Uziyah Garcia died in the shooting, his family confirmed to ABC News.
His grandfather, Manny Renfro, described Uziyah to The Associated Press as "the sweetest little boy that I've ever known."
Makenna Lee Elrod, 10
Makenna Lee Elrod was one of the students killed Tuesday, her aunt, Allison McCullough, confirmed to ABC News.
McCullough described her niece as "a light to all who knew her."
"She loved her family and friends so much," she said.
Alithia Ramirez, 10
ABC News learned that Alithia Ramirez was one of the students killed.
“She was a very talented little girl,” Rosa Maria Ramirez, the grandmother of Alithia, told ABC News. “She loved to draw.”
Ellie Garcia, 9
Ellie’s mother confirmed to ABC News that she is one of the victims killed in the shooting.
Nevaeh Bravo, 10
A family member confirmed that 10-year-old Navaeh Bravo was killed in the shooting.
Alexandria Aniyah Rubio
Alexandria Aniyah Rubio, a honor student at Robb Elementary school was killed in the attack on the same day she received a good citizen award from her school, according to her family.
"My beautiful, smart, Alexandria Aniyah Rubio was recognized today for All-A honor roll," the girl's mother, Kimberly Mata-Rubio wrote on Facebook the day her daughter died. "She also received the good citizen award. We told her we loved her and would pick her up after school. We had no idea this was goodbye."
The family of Tess Mata confirmed to ABC News that the 10-year-old was killed in the shooting.
"Every time we would see another mass shooting on the news we would say, 'that won’t happen here,'" Tess' mother, Veronica Mata, told ABC News. "That could never happen here. Not in Uvalde."
Veronica Mata said now her daughter is gone and she "will never get to hold her again."
Layla Salazar, 10
Layla Salazar was among the victims in the shooting, her father, Vincent Salazar, told The Associated Press.
Vincent Salazar would play "Sweet Child O' Mine" by Guns N' Roses as he drove her to school each morning, and Layla would sing along, he said.
Maite Rodriguez, 10
In an interview with The Associated Press, Maite's mother said, "She was charismatic. She was goal-driven. She was ambitious. She was determined. She was focused. She was competitive, smart, bright, beautiful, happy."
"Why I want the world to know?" Maite's mother added. "Because I don't want her just to be another kid. I don't want her just to be another face. I don't want any of those kids to be just another face. Each one of them has a story to tell. And this just horrendous act just cut everything short for them."
Jose Flores, 10
Christopher Salazar, an uncle of Jose Flores, wrote on Facebook: "I love you and miss you."
Maranda Mathis, 11
Maranda Mathis is one of the victims, her mother confirmed to ABC News. Maranda’s brother Bruce, a second-grader, was also at the school but was not injured.