The alleged gunman -- identified by authorities as 18-year-old Salvador Ramos, a student at Uvalde High School -- was killed by law enforcement at the scene.
The suspect allegedly shot and injured his grandmother before opening fire at the school, officials said.
Matthew McConaughey calls for action after shooting
Actor Matthew McConaughey decried the shooting in his hometown of Uvalde, Texas.
"We have tragically proven that we are failing to be responsible for the rights our freedoms grant us," he wrote in a statement on Twitter.
"We cannot exhale once again, make excuses, and accept these tragic realities as the status quo."
May 25, 2022, 4:55 AM EDT
Amanda Gorman pens poem about shooting
The 24-year-old National Youth Poet Laureate took to Twitter following the tragedy to share a poem.
She also posted a series of tweets on gun violence.
“It takes a monster to kill children,” she wrote. “But to watch monsters kill children again and again and do nothing isn’t just insanity -- it’s inhumanity.”
Adults comfort a girl crying outside the civic center in Uvalde, Texas, May 24, 2022, following a shooting at an elementary school.
President Joe Biden addressed the nation Tuesday night following the mass shooting in Texas -- not even two weeks after he mourned victims of the mass shooting in Buffalo, New York.
"I’d hoped, when I became president, I would not have to do this again," Biden said. "Another massacre. Uvalde, Texas. An elementary school. Beautiful, second-, third-, fourth-graders."
President Joe Biden makes a statement about the school shooting in Uvalde, Texas, shortly after Biden returned to the White House from his trip to South Korea and Japan, May 24, 2022.
Kevin Lamarque/Reuters
"As a nation, we have to ask when in God's name are we going to stand up to the gun lobby," he said. "I am sick and tired of it -- we have to act."
Connecticut Sen. Chris Murphy pleads with lawmakers after shooting
Connecticut Democrat Chris Murphy gave an impassioned argument on the Senate floor to his colleagues late Tuesday afternoon, hours after 21 were killed in the mass shooting.
"What are we doing?" Murphy asked the chamber. "There have been more mass shootings than days in the year."
"Our kids are living in fear every single time they set foot in the classroom because they think they're going to be next. What are we doing?"
For Murphy's remarks and full coverage, click here.