The students stood silently on the Howard University quad Thursday night and grasped red bags of Skittles high over their heads in memory of Trayvon Martin.

Martin, a 17 year-old African American teen, was fatally shot in Sanford, Fla., last month by George Zimmerman, a neighborhood watch volunteer who said he suspected Martin of mischief. Martin was unarmed, carrying a bag of Skittles and a bottle of iced tea.

Martin’s shooting has sparked nationwide furor, a federal civil rights investigation and calls for the arrest of Zimmerman, who claimed the shooting was in self-defense.

Daniel Cokes, organizer of the Howard University protest, said squeezing those treats was proof of life for the 150 or so students who gathered. Cokes, a senior legal communications major, called on his peers and others to fight for improvements in the legal system and to draw attention to what he said was the injustice of Martin’s death.

Protesters joined around the flagpole at the center of campus, prayed and sang “Lift Every Voice and Sing.” They also began organizing for other marches and demonstrations.

Corryn Freeman, a senior political science major, urged attendees to stay involved and to take part in future protests to demand a deeper investigation and the arrest or indictment of Zimmerman.

“Zimmerman exercised excessive use of force,” Freeman told the crowd. “He committed nothing less than murder.”

The event was organized with members of student government, the campus chapter of the NAACP and other organizations.

Brandon Harris, president of the student association, told the crowd that when such incidents go unchallenged, they can continue to spread, like a disease, throughout society. “When you think of injustice, I look at it like cancer,” Harris said. “As we stand here today . . . we have to be the chemotherapy.”