'I'll always have to check who's around me': Students across the country describe fear following Texas shooting

• A gunman killed 21 people including 19 children at a Texas elementary on Tuesday.
• Students and teachers across the country feel scared and anxious.

Kids all across the country have expressed fear and concern about going to school after a gunman fatally shot 21 people at a Texas elementary school on Tuesday.

"Honestly, right now, I'm just feeling a bit vulnerable. And I feel like these shootings are just really reoccurring, and I feel like I can't do anything about it," Erica, a 13-year-old from California told CNN.

Mary Elle, a fifth-grader from New York, told CNN she didn't understand how an 18-year-old was able to just walk into a store and purchase a gun, and now innocent people are dead.

"Now, when I enter my school I won't feel safe as I used to feel. I'll always have to check who's around me," she said.

An 18-year-old gunman opened shot his grandmother in the face before taking her car, crashing it, and running into Robb Elementary School in Uvalde, Texas, and fatally shooting 19 children and two adults. The gunman barricaded himself inside a fourth-grade classroom. Police have offered conflicting accounts of what happened and how long it took law enforcement to respond.

Several reports show that police did not engage with the shooter for as long as an hour.

Teachers across the country are also on edge.

"Check on your teacher friends. We are not okay. Getting shot should not be an 'occupational hazard' for teachers, and definitely not for students. We aren't even paid a livable wage, yet every single one of us goes above and beyond for these kids every day, and I guarantee every single teacher would lay down their life for their students if it came down to it," Laura G, a teacher from Dallas, Texas, told NBC News.

Karen Chappell, a teacher in New Jersey, told the outlet that she could hear "a distinct difference in the sound of children's voices and laughter."

Other teachers said they sat in their classrooms and cried, and were "holding their breath" for the next shooting.

Tyler Sanatan, a teacher in Florida, told NBC News that the end of the year was meant to be bittersweet as he sent his 8th-grade class to high school.

"Now all I feel is fear. My last few days are now spent watching students like a hawk, cringing every time a student opens the door to let someone into the class, worried that I won't be able to go home to my 3-month-old daughter," he said.