violence@ (Adds comment from student survivor, details on efforts to tighten laws)
NEW YORK, March 14 (Reuters) - Students will walk out of classrooms across the United States on Wednesday to demand tighter gun safety laws, joining a movement spearheaded by student survivors from the Florida high school where a gunman killed 17 people last month.
The #ENOUGH National School Walkout, scheduled to begin at 10 a.m. local time across the country, will last 17 minutes, commemorating the 17 students and staff killed at Marjory Stoneman Douglas High School in Parkland, Florida on Feb. 14.
The walkout is part of a burgeoning, grass-roots movement that grew out of the Parkland attack. Some of the survivors have lobbied state and federal lawmakers, and even met with President Donald Trump, to call for new restrictions on gun ownership, a right protected by the Second Amendment of the U.S. Constitution.
"If our elected officials don't take responsibility for their inaction on both sides of the aisle, then we are going to kick them out of office," David Hogg, a Stoneman Douglas student, said in an interview with MSNBC on Wednesday.
The students' efforts helped bring about a tightening of Florida's gun laws last week, when the minimum age for buying any kind of gun was raised to 21 years from 18, although lawmakers there rejected a ban on the sort of semiautomatic rifle used in the Parkland attack.
In Washington, however, plans to strengthen the background-check system for gun sales, among other measures, appear to be languishing.
Students from more than 2,800 schools and groups will participate in the walkout, many with the backing of their school districts, according to the walkout's organizers, who also coordinated the Women's March protests staged nationwide over the past two years.
Support has also come from the American Civil Liberties Union and Viacom Inc, which said all seven of its networks, including MTV, would suspend programming at 10 a.m. in each U.S. time zone during the 17-minute walkout.
The protest will take place a day after Florida prosecutors said they would seek the death penalty for Nikolas Cruz, who has been charged with 17 counts of premeditated murder and 17 counts of attempted murder for the Parkland attack.
Robert Runcie, the Broward County school superintendent, said the district, which includes Stoneman Douglas High School, would respect the free speech rights of students and allow them to participate in the demonstration.
But a few school districts around the country have warned against protests during school hours.
Administrators in Sayreville, New Jersey, told students that anyone who walked out of class would face suspension or other punishment, according to myCentralJersey.com.
The New York City Department of Education said it would allow students to participate if they submitted a signed permission slip from their parents. It would consider the walkout an excused absence.
In Newtown, Pennsylvania, Council Rock School District will designate an area inside schools where students could gather in a "non-political fashion" to remember the shooting victims. Officials will block all entrance and exit points for the duration of the protest to prevent students from walking out.
Robert Fraser, the Council Rock superintendent, sent a warning to parents that any student who walks out of school will face discipline.
More than 40 of U.S. colleges and universities, including Yale, Brown and the Massachusetts Institute of Technology, have said their admissions offices would not penalize any applicants who may be disciplined for protesting.
"I, for one, will be cheering these students on from New Haven," Hannah Mendlowitz, an admissions and recruitment official at Yale University, wrote in a blog post in February.
(Reporting by Gina Cherelus in New York; Additional reporting by Jonathan Allen in New York and Susan Heavey in Washington; Editing by Frank McGurty and Lisa Shumaker)