(CNN) A gunman opened fire at Saugus High School in Santa Clarita on Thursday morning. It's a reality many students there had been fighting to end.

They joined the March For Our Lives movement. They held town halls with local leaders. Their California school developed an in-depth safety plan in case a day like today ever came.

After the mass shooting at Marjory Stoneman Douglas High School in Florida, Saugus High students joined thousands in nationwide walkouts in March 2018, leaving their classrooms for 15 minutes to protest gun violence, the Santa Clarita Valley Signal reported at the time.

The next month, a few of them hosted a gun control town hall with local leaders advocating for safer schools.

"It's very easy to look at today's politics and make quick judgments," Saugus High student Lèan Aguilar said in April 2018. "What isn't easy is having a one-on-one conversation with one another, and engaging in this town hall."

Former Rep. Katie Hill, a Saugus High School alumnus, told CNN that students at the school interned for her campaign. Many of them feared the day a school shooting would strike their campus.

"It's almost like the students I have worked with over the course of the campaign knew it was going to be coming," she said. "It was only a matter of time."

Saugus mom says the neighborhood is safe

More than 2,480 students attend the school, located around 40 miles from downtown Los Angeles, according to the California Department of Education . It's one of the largest high schools in a district of 24,400 students.

Hannah de Caussin told CNN she was surprised a shooting happened in their Saugus neighborhood.

"This is a safe area and we are all shocked," she said.

She said her daughter and her four friends are staying in her home for safety. Her home is close to the school, so she's keeping it open for students running away.

"I have a handful of kids here, safe, waiting for more info. The school sent a text not to go to school today," she said.

This is a developing story. More to come