Hundreds of people, including the music superstars Jay-Z and Beyonce, have assembled in New York City at one of the rallies being held around the country calling for "justice" for slain teenager Trayvon Martin.

Trayvon Martin's mother Sybrina Fulton speaks at a podium as Trayvon Martin's brother Jahvaris Fulton (L) and Rev. Al Sharpton attend a rally (Kena Betancur/Getty Images)

Martin's mother, Sybrina Fulton, and the Rev. Al Sharpton were leading the vigil on a plaza in downtown Manhattan.

It comes a week after a Florida jury found George Zimmerman not guilty in the killing of the unarmed teenager.

In addition to pushing the Justice Department to investigate civil rights charges against Zimmerman, Sharpton says he wants to see a rollback of stand-your-ground self-defense laws, which are on the books in more than 20 states.

Sharpton's National Action Network organized midday "Justice for Trayvon" rallies and vigils outside federal buildings in about 100 cities.

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