Thousands of students across the nation were walking out of classrooms Wednesday to mark one month since the bloody rampage at a Florida high school that shocked the world and fueled a dynamic youth movement demanding an end to gun violence.

Students from almost 3,000 schools were marking National Walkout Day, most by leaving their classrooms at 10 a.m. local time to show solidarity for the 17 killed in the Valentine's Day attack at Marjory Stoneman Douglas High School in Parkland.

In Parkland, students gathered on the football field, embraced and chanted "MSD!" and "We want change!" Then, rejecting requests from administrators to return to classes, they joined with students from a nearby middle school to walk two miles to memorials set up for the victims.

At Columbine High School south of Denver, hundreds of students solemnly filed onto the soccer field for a short rally during which they released balloons to memorialize the Stoneman Douglas students, along with the 13 people killed at their own school 19 years ago.

“We should never go to school in fear of our lives,” said sophomore Leah Zundel, 15, as her voice broke. “Enough is enough.”

In Washington, several hundred students of all ages massed outside the White House, waving signs and shouting "What do we want? Gun control! When do we want it? Now!"

Bella Graham, a seventh-grader at Takoma Park Middle School in Maryland, said she thought she needed to support the students in Parkland.

“I shouldn’t have to be here,” said Graham, armed with a sign that read “an assault on our future” with a photo of a rifle. “I should be in school, but we have to stick up for ourselves and say enough is enough of this violence."

While the protests rolled on, Democrats in the U.S. Senate took to the floor for a series of speeches in which they read the names of young people killed by gun violence. Sen. Richard Blumenthal, a Democrat from Connecticut, where the Sandy Hook tragedy took place more than five years ago, said the protesting students' "energy and passion is a civics lesson for America."

In Indiana, 17 students at Herron High School near downtown Indianapolis stood in a circle and held photos of those who died in Parkland. Hundreds of students held signs reading "Never again" and "Enough is enough." Some chanted "Make change now!" and "We deserve better!"

In some cities, the message was mixed. In Vero Beach, Fla., about 100 miles north of Parkland, scores of students gathered around a flagpole where their cries of “We want change!” and “Am I next?” were at times met with other students chanting “Trump!” and “We want guns.”

Students at Philadelphia High School of Creative And Performing Arts participate in a walkout to address school safety and gun violence on March 14, 2018 in Philadelphia, Pennsylvania.
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At others schools, administrators discouraged the protests, warning that participation could result in disciplinary actions. Curtis Rhodes, superintendent for Needville Independent School District, about 40 miles southwest of Houston, said disruptions wouldn't be tolerated because "a school is a place to learn" and vowed to suspend all students participating.

In South Carolina, the Greenville school district barred the news media from schools during the protests. District spokeswoman Beth Brotherton said a student protest for gun-control measures is a divisive issue, that students should instead "focus on kindness." Many students at J.L. Mann and Hillcrest high schools walked out anyway.

But at most schools, staffers have been accommodating to the planned demonstrations — some even cheering on students.

In New Jersey, about 1,000 students silently walked the perimeter of Plainfield High School. Some school staff joined them.

“I am very proud of our students,” performing arts teacher Shaniesha Evans said. “This was their idea and this is what they wanted to do.”

In Haddonfield, N.J., teachers held their own march before school. About 100 students, teachers, parents and administrators came together, many carrying signs or wearing orange ribbons.

"This walk is our way of showing our students we support them and believe in keeping them safe," said Stacey Brown, an English and special education teacher at Haddonfield Memorial High School.

Thousands of local students sit for 17 minutes in honor of the 17 students killed last month in a high school shooting in Florida, during a nationwide student walkout for gun control in front the White House in Washington, DC, March 14, 2018.
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In Nevada, hundreds of North Valleys High School students filled the stands of their football stadium in Reno to release 17 balloons and hold a 17-second moment of silence. Freshman Marina Johnson held a sign that said "Your children not your guns."

"The memorial service is great," she said. "But we can't just have a memorial service every time this happens."

In Michigan, North Farmington High School students wore T-shirts with the hashtag #enough on the front and the names of the Florida shooting victims on the back. The students observed a six-minute moment of silence — the amount of time it took the Florida shooter to kill 17 people. Then they read the names of the victims — one every 17 seconds.

Wednesday's walkouts marked the first in a series of events in March and April organized by students across the nation as part of the #NeverAgain movement. Another walkout is scheduled on April 20 to mark the 19th year since the Columbine High School massacre.

A massive rally dubbed March For Our Lives is planned March 24 in Washington. The event is expected to attract 500,000 people and has spurred sister marches in every state.

On Wednesday, students were expected to demonstrate in different ways. Students at the University High School in Tucson, Ariz., will recite the names of the students and school administrators who died in Parkland and make plans to flood local lawmakers with calls about addressing gun violence.

"My peers and I feel there is no time more critical than this to make clear that we have had enough of gun violence," said Deja Foxx, a senior at the high school. "For far too long, it has made us feel unsafe in our communities and in our classrooms."