Yesterday, a mass shooter opened fire on innocent children and teachers at Robb Elementary School in Uvalde, Texas. The Uvalde school shooting has claimed the lives of at least 21 people—19 of them children in second, third, and fourth grade.

A mother of a third-grader at Robb Elementary, Evelyn, tells PEOPLE that parents were notified of an active shooter via the school's automated system. The surviving children were moved to a nearby civic center to be reunited with their parents.

"I didn't know if my son was alive or dead, I didn't know what was happening," Evelyn said.

She describes the scene as a "nightmare," saying that she—along with many other parents—aimlessly walked around waiting for news. She added that the possibility of a school shooting has been something she's been afraid of her entire life.

Related: An age-appropriate guide for how to talk to your kids about school shootings

"I see the school shootings and I think this is a small city and that happens in big cities, but it happened here and it almost killed my son."

Evelyn, her husband, and her 9-year-old son were among the fortunate families to be reunited at the civic center. She said they were all crying as they embraced and that her son was scared.

"He was like 'Mama, Mama, Mama' and we hugged and I cried. I told him he was very brave, and I hugged and kissed him a lot. I keep hugging and kissing him because I know he is here with me and I am happy."

Evelyn and her husband came to the U.S. nearly 10 years ago, before her son was born. She tells PEOPLE that in the immediate aftermath of the shooting that nearly claimed her son's life, she's too terrified to continue sending him to school in the U.S.

"I do not want my son to go to school in America anymore, I want to go back home and he will be safe there," she says. "This is too dangerous."

As of 2020, firearms became the leading cause of death in children. According to the New England Journal of Medicine, firearm-related deaths increased 13.5% between 2019 and 2020, but such fatalities for those 1 to 19 years old jumped nearly 30%.

In addition to the fatalities, more than a dozen other people were injured in the Uvalde school shooting—including more children and police officers. Survivors are currently being treated at surrounding hospitals.

The suspected gunman was identified as an 18-year-old who attended a nearby high school. He was fatally shot by police after the shooting, according to Texas Gov. Greg Abbott.

Related: Here’s why the AAP supports gun control

The American Academy of Pediatrics (AAP) has long supported stricter gun control legislation, and in the wake of the Uvalde school shooting, the AAP is calling for an end to inaction.

“When will we as a nation stand up for all of these children? What, finally, will it take, for our leaders in government to do something meaningful to protect them?" the organization says in an official statement. "The AAP has called on the federal government to increase funding for research into gun violence prevention and for common-sense laws that protect everyone in a community. There are things that we can do, but it will require a unified approach."

As for Evelyn and her family, she tells PEOPLE that she doesn't know how to go on after experiencing such a horrific—yet preventable—tragedy that so many other families across this country have also faced.

"I will not sleep. I can never sleep thinking of this. When I close my eyes, I will think of these children, and I will think of my son and I will not sleep. It will be too hard."