Phoenix, Arizona (CNN) -- Hundreds of people gathered outside Arizona's Capitol building on Sunday in a largely peaceful protest against the state's tough new immigration law. Chanting "Yes we can," waving American flags and holding signs reading "We have rights" and "We are human," demonstrators kept up a festive spirit as they denounced the bill signed Friday by Gov. Jan Brewer. The new law requires police to determine whether a person is in the United States legally. It also requires immigrants to carry their alien registration documents at all times and requires police to question people if there is reason to suspect they're in the United States illegally. Protesters worry that the law will foster racial profiling.