(CNN) - It used to be that Moms Demand Action for Gun Sense In America, created the day after the 2012 Sandy Hook shooting, could count on maybe 20 people at their regular meetings.
The mass shooting at Marjory Stoneman Douglas High School in Florida has changed all that.
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Now the group's leaders say they are scrambling to make room for 75,000 volunteers who have joined their ranks since last week's massacre.
More than 500 people showed up for a recent Raleigh, North Carolina, meeting, where organizers opened a spill room to accommodate the new volunteers. Instead of the usual 20 people or so at a meeting near Portland, Maine, 250 volunteers showed up.
Moms Demand Action founder Shannon Watts says she is seeing a new generation of youth ready to fight for more gun regulations. Tired of the lack of progress on addressing gun violence in schools, these young people are motivated to seek change, she said.
"This next generation is angry," Watts said. "They've spent their whole lives doing active-shooter drills."
Watts says her group's job is to prepare these volunteers for an arduous battle toward enacting stricter gun laws. Her group is set to help the newly created Students Demand Action group with funding, training and organizing. They are also preparing them mentally to lower expectations that their efforts will bring immediate action.
"We all want a cathartic moment in Congress," she said. "I'm hopeful. But even if it doesn't happen, we have to keep the conversation going."
The young volunteers will be trained to do research, meet with lawmakers and sit in on statehouse gun-legislation hearings. The organization is hosting a teleconference tonight with participants nationwide.
Judging by turnouts in recent days, their movement has already begun. On Tuesday, Minnesota legislators had to walk a gauntlet of about 200 gun-control activists to enter their statehouse in St. Paul. And in Atlanta, organizers moved their protest staging area outside the state Capitol to make room for an unexpected flood of 400 volunteers.
Past polling has shown that support for gun-control measures goes up after mass shootings. But in recent years such sentiment has rarely resulted in legislative action.
Nevertheless, Watts says that with a growing numbers of mass shootings in their short lifetimes and eight school shootings already in 2018, today's younger generation is energized to fight the status quo.
"They are angry," she said. "They've been vulnerable while lawmakers are acting like shootings are acts of nature like a fire instead of disarming dangerous people."
CORRECTION: A part of Sharon Watts' quote in an earlier version of this piece has been corrected.
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