Around 40 Marjory Stoneman Douglas alumni in the Bay Area are among the thousands who attended the marches in San Francisco, San Jose and Oakland, according to alumni David Nassau who attended the rally in Oakland on Saturday.
"We have to let the community know that we have their back. Oakland is not that different of a place than Florida," Nassau told NBC Bay Area.
Nassau joined student activists and gun control advocates in the Bay Area, and across the nation, to rally behind Marjory Stoneman Douglas High School students who formed the organization in the aftermath of the Parkland, Florida, shooting which left 17 people dead.
Sen. Dianne Feinstein spoke at the Civic Center Plaza in San Francisco asked the crowd: "Is this the country we want our children to grow up in?"
"I’ve been fighting to get weapons of war off our streets and out of our schools since I was first elected. Never have I seen this passion, this energy, this determination to get #GunReform passed and make our communities safe again!," Feinstein tweeted.
More than 25,000 people said they would attend the rally in San Francisco but it was unclear how many people showed up.
One of the attendees in San Francisco, 13-year-old Benje Choucrouni, said he's at the march because he wants to "protect" students in schools so they don't get killed like those in Parkland and other school shootings.
One of the cities in the Bay Area that saw big crowds is Oakland, where TV host Nev Schulman and comedian W. Kamau Bell attended the rally.
Approximately 2,000 attendees were at Frank H. Ogawa Plaza in downtown Oakland, according to Oakland Police. The rally was peaceful and there were no reports of arrests, citations, vandalism or injuries, police said.
Oakland City Counsilmember At-Large Rebecca Kaplan said that it's not only important to have a conversation about gun violence when it happens to a large group, but the "daily fear of gun violence that plagues so many of our communities" has to be a part of it too.
One of the marchers in San Jose, Terri Possley, told NBC Bay Area that she is marching for her cousin Jordyn Rivera, 21, who died in the shooting in Las Vegas massacre in October.
"Jordyn pushed me here to come," Possley said. "I'm just inspired by the students who led us here. I just wish for the day we can all be safe going to schools, concerts, going to the trains, subways."
The organizer of the San Francisco rally Shoshana Ungerleider said she put the event together on Facebook after she didn’t see one planned.
"The poise and composure of the Parkland students standing up and saying to the country enough is enough," Ungerleider said.
Lowell High School freshman Jason Chen, who partook in the school walkouts on Mar. 14 to bring attention to school safety and gun violence, said "We’re going to have a big front line of diverse passionate and loud student."
"I want lawmakers to actually pass common-sense gun reforms. This doesn’t mean they should arm teachers, this doesn’t mean they just overlook it and stay silent," Chen said.
More than 700 sister marches planned for every state in the country.
In all more 800 protests are planned throughout the world, most in the United States and Europe.
"I'm so heartened by the fact that people around the country and people in the Bay Area are getting behind the student-led effort to make change," Ungerleider said.
The Associated Press contributed to this report.