Local police say 100,000 people had gathered in the streets of Rio de Janeiro, building on big protests in Sao Paulo and other Brazilian cities this week. Protesters say they're angry over a lack of public services, economic instability, government corruption, and police brutality. (See "Playing Rio.")

Much of the online conversation around the photo has been marked by shock and revulsion. "It seems that the most dangerous thing the woman is carrying," wrote Business Insider, "is a cigarette."

The photographer who shot the picture, Victor Caivano, told New York magazine that the woman in the shot was standing alone at around 11:20 p.m. on a "deserted corner" after the police had cleared the area of rioters.

"Three riot officers