Thousands of protesters on Monday demanded justice for an unarmed black Florida teenager whose killing a month ago has sparked a national uproar and re-opened wounds over US racial tensions. The crowd of about 8,000 marched through the streets of Sanford to present a petition to civic leaders with more than two million signatures demanding that a neighborhood watch guard be prosecuted for gunning down 17-year-old Trayvon Martin last month. \"Justice for Trayvon,\" the crowd chanted. The march was led by Martin\'s parents, Tracy Martin and Sybrina Fulton, as well as civil rights leaders Al Sharpton and Jesse Jackson. \"This case demonstrates profound racial inequality, not only juvenile -- it also demonstrates the racial profiling in this country,\" Jackson told AFP. He also highlighted \"the racial profiling in the criminal justice system, police departments, also with the banks as well, and it\'s going on for too long.\" Sharpton called the case a \"terrible travesty of justice.\" \"I am committed to stay with this until we get justice,\" he told AFP. \"We will stay here until we see this through.\" The petition, launched online by the activist group Change.org, calls for George Zimmerman, 28, to be investigated and charged after fatally shooting Martin on February 26. It was to be handed to the mayor and city commissioners, who were holding a scheduled monthly meeting at the Sanford civic center. Zimmerman says he shot the teenager out of self-defense after an argument erupted in the gated community. The Orlando Sentinel Monday said Zimmerman had told police Martin felled him with one punch and then climbed on top of the neighborhood watch guard and slammed his head into the sidewalk several times. Zimmerman, who is a white Hispanic, has not publicly spoken about what happened, but several witnesses confirmed his account to the daily Sentinel. But Martin\'s death has sparked an outrage, with rights groups saying it was again proof of racial profiling of black people. Meanwhile, the city named Darren Scott as interim police chief after Police Chief Bill Lee stepped aside due to the investigation. Lee had come under fire because no charges have been brought against Zimmerman and he has not been detained in the case. Nathalie Jackson, an attorney for the Martin family, claimed Monday there was enough evidence against Zimmerman. \"Clearly, the investigation in this case was either bungled, or ignored completely,\" said Jackson. US President Barack Obama, the nation\'s first African-American president, stepped into the highly-charged debate on Friday calling for \"national soul-searching\" over the tragedy. \"If I had a son, he\'d look like Trayvon,\" Obama said in an unusually personal take on the case which has once again brought America\'s long-simmering racial tensions to the fore. In the Miami suburbs where Martin lived with his mother, hundreds of students went to school Monday dressed in black at the high school he attended in a protest over his death. \"This is something that happened because of racism, for sure, and all I want is justice... for my friend,\" said 16-year-old Joel Escarment. The city erected a jumbo screen outside the civic center to broadcast the meeting to the throngs of demonstrators. Meanwhile Governor Rick Scott has appointed Angela Corey as a special prosecutor to investigate the case, with a grand jury scheduled to begin deliberations on April 10.