Hundreds of students at one Reno high school chanted, "We want peace," as they marched several blocks to a U.S. Post Office to deliver letters to their members of Congress demanding action to combat gun violence.

Wooster High senior Ann Snelgrove said they have to put pressure on politicians who refuse to do their job because they're paid off by the gun lobby.

She said in a speech outside the post office Wednesday that those who oppose expanded background checks are on the wrong side of history. She asked, "Can't you hear the children scream?"

Freshman Lily Crano carried a sign referencing the mass shooting in Florida that read, "They could have been us." Cano told us the Parkland shooting was her tipping point, "Seeing all these children die, all these people try to help them and nobody's doing anything, no one's helping them--there's no change."

Fighting through tears, Cano added, "I want them to protect our children, I want them to protect us while we're in school. I want to feel safe wherever I am. I don't want to be scared of an AR-15 in my school because I'm trying to learn."

Wooster High students are organizing another walkout, set for April 20th--the anniversary of the Columbine High School shooting.

Students at more than 3,000 schools across the country are expected to participate in walkouts - one month after the deadly shooting at Marjory Stoneman Douglas High School in Parkland.

Students are standing in solidarity for 17 minutes, to remember the students who lost their lives and encourage Congress to reform gun laws.

"We are at school and we are perfectly fine, nothing happened to us and we can come to school but we don't know nothing won't happen," says Reed High School Sophomore, Brianna Kistner. 

Some local students are joining the walkout, regardless of any consequences. Washoe County School District sent out a letter to parents and students regarding the walkout stating, "We have provided guidance to all of our school sites suggesting that site leaders consider a school-wide event on the days in question to provide meaningful engagement for all students." 

It goes on to say the activities should challenge students to learn about civic engagement but if students participate in the walkout, it will be considered an unexcused absence. For the full letter, click here.

Although some students believe there are other ways to protect our schools other than gun control. "We should probably get better security in schools, up the cops, at least have some trained staff on campus to protect the students better," says Reed High School Junior, Matt Vannorsdall.

As for parents, some say they like that students are engaging in the political process. "Attending some public meetings or doing a march from school to school or doing something after school or the weekends I believe if they did something after school I think they will be taken more seriously," says parent Dawn Hepner.

Some are skeptical of other student's motives. "I have been asking people if they know what they are walking out for, the reason for it this is a big deal and they go 'no I just want to get out of class' and that is not an okay to do it," says sophomore Nick Stevens. 

Meanwhile, South Carolina's largest school district says it's going to reprimand several hundred students who participated in a national walkout to protest gun violence at schools.

Greenville County Schools spokeswoman Beth Brotherton said Wednesday that students who participated in the walkout will be cited for cutting class. She said school records show that about 530 students participated at about a dozen high schools.

The high schools with the most participation were J.L. Mann Academy in Greenville, with about 200 students walking out; and Maudlin High School with about 180. Overall, the district has about 77,000 students.

District officials had said before the walkout that they were discouraging students from participating and didn't plan to allow news media to cover the activity.

And - the National Rifle Association has sent out a defiant tweet that included a picture of an assault-style rifle and a comment saying: "I'll control my own guns, thank you."

The tweet was posted Wednesday morning as students around the country staged school walkouts to protest gun violence. The NRA has come under increased criticism since last month's shooting. The gunman in that shooting used an AR-15 assault rifle.

(The Associated Press contributed to this report.)