The shooting at Robb Elementary School in Uvalde, Texas, that left at least 19 children and two teachers dead is now the second-deadliest shooting at an elementary, middle or high school in the United States.
In its wake, survivors of past school shootings are speaking out to share their grief and anger that a school is once again the site of a deadly shooting.
"No no no no not again," tweeted Lauren Hogg, who survived the Feb. 14, 2018, shooting at Marjory Stoneman Douglas High School in Parkland, Florida, that killed 17 students and staff.
"Heartbroken," she wrote. "Thinking of the families going through what no one should ever have to go through (right now) and the young kids who will be dealing with this trauma for the rest of their education and their lives."
Hogg's brother, David Hogg, who, like many Parkland survivors, has become a vocal advocate for gun reform, tweeted that change after this most recent school shooting needs to be different.
"No more debate or thoughts and prayers," he wrote. "We need bipartisan action."
"America will continue to be a hub and epicenter of gun violence until the people in power decide to take action," another Parkland survivor, Alex Wind, wrote on Twitter. "There is no more time for thoughts and prayers."
At Robb Elementary School, among those killed were third and fourth grade students and a fourth grade teacher.
Amerie jo Garza's father, Angel Garza, told ABC News that his daughter just turned 10 two weeks ago; her birthday was May 10.
Fourth-grader Xavier James Lopez was another victim of Tuesday's 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.
Fred Guttenberg, whose 14-year-old daughter Jamie died in the Parkland shooting, wrote on Twitter that he was "speechless" after learning more parents would get the news that their child died at school.
Guttenberg became a gun safety advocate in the wake of his daughter's death.
Student survivors like Hogg formed their own activist group, March for Our Lives, to call for gun control reform.
Jaclyn Corin, a March for Our Lives co-founder, wrote on Twitter, "Innocent children will only continue to die if we don’t end the gun problem in America."
Another Parkland survivor, Aalayah Eastmond, tweeted Tuesday, "I don't even know how to process this anymore."
"Are you kidding me? I’m so disgusted, angry, fed up, & hurt," she wrote.
The tragedy in Uvalde, about 90 minutes west of San Antonio, came just days after another deadly mass shooting in Buffalo, New York.