After a school shooting in Texas in which at least 19 children and two teachers were killed, teachers are speaking out about the fear they experience daily for themselves and their students.

Angelle Terrell, a high school social studies teacher for 11 years, said she felt compelled to speak out after hearing about the shooting Tuesday at Robb Elementary School in Uvalde, a small town about 90 minutes west of San Antonio, Texas.

Two fourth grade teachers, several sets of cousins and a 10-year-old boy whose family called "the life of the party," were among those killed in the mass shooting, ABC News has learned.

"I just felt that I needed some sort of release because, as a teacher who thinks about all of those things all of the time, I just couldn’t keep them under wraps anymore," Terrell told "Good Morning America." "I felt like I wanted to say what I always think in the wake of some sort of mass shooting."

Terrell, of Baton Rouge, Louisiana, took to Facebook to share in a now-viral post all the things teachers think about due to the rise in school shootings over the past decade.

"Every teacher you know has thought about it. Every teacher you know has a plan for an active shooter," wrote Terrell. "Every teacher you know has weighed their point of fight or flight. Every teacher you know has walked their room looking for blind spots."

"Every teacher you know has passed their classroom to see what it would look like from the outside," she continued, in part. "Every teacher you know has wondered how fast they can lock a door."

"Every teacher you know has had a talk about the "spread out" or "group together" methods. Every teacher you know has gotten jumpy at least once at the sound of a fire alarm, unplanned announcement, or screech from the quad," Terrell continued. "Every teacher you know has wondered if they could be in the way long enough to prevent damage. Every teacher you know has thought about how hard it would be to keep 25 young people quiet."

Every teacher you know has walked into a different classroom and noticed where the doors and windows are. Every teacher you know thinks it can happen, so they pray it doesn't," she wrote. "Every teacher you know."

"And, at some point in their lives, children in a classroom think at least one (if not all) of these things as well," Terrell ended her post. "I'm just sick. Heartbroken and sick."

Since Tuesday, Terrell's post has been shared over 4,000 times and has received hundreds of comments, many from other teachers voicing their similar experiences.

"Every year, we start our trainings not with curriculum or assessment but with active shooter training," wrote one commenter. "We literally prepare for this. It is dreadful."

"Truth. I have toys in my bathroom just in case we need to stay and be quiet," wrote another. "Sad but reality."

Terrell said she left classroom teaching last November, mostly in order to spend more time with her children, ages 3 and 5.

She said she remembers being a student herself when the deadly school shooting at Columbine High School happened in Littleton, Colorado, in 1999, and then a second-year teacher when 26 people were killed at Sandy Hook Elementary School in Newton, Connecticut, in 2012.

"The news came through and my high school students brought it to my attention and we wept," she said of the Sandy Hook mass shooting. "I just thought I was in a parallel universe where this won’t ever happen again because it’s so awful."

In the past decade since the Sandy Hook shooting, the United States has endured more than 3,500 mass shootings, according to the Gun Violence Archive.

In 2022 so far, there have been more than two dozen school shootings in the U.S. resulting in injury or death, according to Education Week."To continuously go back to the classroom where there is just not substantial change is devastating, and it makes you feel numb sometimes," said Terrell. "You have these feelings of grief and frustration and numbness and you feel like no one is listening, but at the same time, you have to be on high alert all the time."

Terrell said once she became a parent herself five years ago, she felt the threat of school shootings even more acutely as both a teacher and a mom.

"You just think about laying down your life for your students, and you think about, well, what's going to happen to your own kids," she said. "As a parent, you think about it all the time, what if this is the last time I see my children, in a place where they're supposed to be the safest? It just shouldn't be like that."

At Robb Elementary School, the two teachers who lost their lives in the shooting, Irma Garcia and Eva Mireles, were both parents and also co-teachers in the same fourth-grade classroom for five years.

According to the district's website, Garcia had been teaching for 23 years, all spent at Robb Elementary School.

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.

Mireles had been a teacher in the school district for approximately 17 years, her aunt, Lydia Martinez Delgado, confirmed to ABC News.

"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 to especially to loved ones."

ABC News' Meredith Deliso, Kiara Alfonseca, Miles Cohen and Mary Kekatos contributed to this report.