NEW YORK (AP) - Tens of thousands of demonstrators of all ages gathered at a "March for Our Lives" rally in New York City on Saturday, at one point holding a moment of silence to honor 17 people killed during a school shooting in Florida just last month.

Sam Hendler, a 16-year-old student from Marjory Stoneman Douglas High School in Parkland, Florida, was at the rally to read the victims' names.

Another student from the school, Meghan Bonner, grew emotional as she told the demonstrators that she wasn't surprised when she learned the identity of the shooter because it was obvious something was wrong with him.

"There was so much more that could have been done to prevent this," she said, fighting back tears. "I want to see change."

The rally in midtown Manhattan was one of several being held across the United States on Saturday in response to gun violence.

U.S. Senate Minority Leader Chuck Schumer, Gov. Andrew Cuomo and New York Mayor Bill de Blasio were among the Democratic Party politicians who joined the march. Former "Sex and the City" star Cynthia Nixon, who's running against Cuomo in the Democratic primary in September, posted a photo on Twitter of herself with family members and others at a subway station on the way to the event.

MORE: Photos from March For Our Lives event in Washington

Celebrities included Paul McCartney, whose Beatles bandmate John Lennon was killed by a gunman in 1980 not far from where the march took place. His T-shirt had the message, "We can end gun violence."

Gianna Serro, a 12th grade student at North Bergen High School in New Jersey, had traveled to the protest with two classmates.

"We are the mass shooting generation, basically," Serro said. "Me being 18, spending 13 years in the school system, I've been raised with lock-down drills because you never know who's going to come in. I've never known any different. ... I believe it's important because we desperately need a change."

Brandi Powell, 19, there with two friends from New York University, said she had been inspired by the actions of the Parkland students.

"We believe we need to see the end of gun violence," she said. "We think that we should have a policy change to ban bump stocks and to ban assault weapons."
  

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AP Radio Correspondent Julie Walker contributed to this report.