victims@ (Adds quotes from students, details from walkouts)
NEW YORK, March 14 (Reuters) - Students walked out of classrooms across the United States on Wednesday, waving signs and chanting their demands for tighter gun safety laws, joining a movement spearheaded by survivors of the deadly shooting spree at a Florida high school last month.
The #ENOUGH National School Walkout began at 10 a.m. EDT (1400 GMT) with 17-minute walkouts planned at 10 a.m. in each time zone, commemorating the 17 students and staff killed at Marjory Stoneman Douglas High School in Parkland, Florida, on Feb. 14. The massacre was the latest in a series of shootings that have plagued U.S. schools for nearly two decades.
Some students got in an early start. At Fiorello H. LaGuardia High School in New York City, crowds of students poured into the streets of Manhattan, many dressed in orange, the color of the gun-control movement.
"Thoughts and prayers are not enough," read one sign, needling the rote response many lawmakers make after mass shootings. At 10 a.m., the hundreds of students sat down on the sidewalk, filling half a city block, and fell silent.
In Parkland, thousands of students slowly filed onto the Stoneman Douglas school football field to the applause of families and supporters beyond the fences as law enforcement officers looked on. News helicopters thrummed overhead.
Ty Thompson, the school's principal, called for the "biggest group hug," and the students obliged around the 50-yard line.
The walkouts were part of a burgeoning, grassroots 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.
"We don't feel safe in schools anymore," Sarah Chatfield said. A 15-year-old high school student from Maryland, Chatfield had joined a crowd of hundreds protesting outside the White House, with some sitting silent with their backs turned.
"Trump is talking about arming teachers with guns," she said. "That is not a step in the right direction."
Soon after, some of the students began marching toward Capitol Hill. "Hey hey, ho ho, the NRA has got to go!" they chanted, referring to the powerful gun-rights interest group, the National Rifle Association.
The Parkland survivors' 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 are joining the walkouts, many with the backing of their school districts, according to the event'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, suspended programming on the East Coast during the 17-minute walkout there.
The protests took 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 in the Parkland attack.
The New York City Department of Education allowed students to participate if they submitted a signed permission slip from their parents.
But a few school districts around the country had 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.
(Reporting by Gina Cherelus in New York; Additional reporting by Jonathan Allen and Alice Popovici in New York, Joe Skipper and Bernie Woodall in Parkland, Florida, and Susan Heavey and Ian Simpson in Washington; Editing by Scott Malone and Jonathan Oatis)