One vagrant died and three were badly beaten in overnight attacks in Brazil's biggest city of Sao Paulo, raising the number of victims of a suspected death squad to 14 in four days. Security officials said on Sunday the attacks again happened in Sao Paulo's city center. It is busy during work hours but gets desolate at night and over the weekends. On Thursday night, four tramps were killed and five battered unconscious. The murders happened against a background of rising kidnappings and muggings in this already violent city -- South America's largest. "We are intensifying patrols in the streets. This appears to be an organized operation," said urban security secretary Benedito Domingos Mariano. State prosecutor Carlos Cardoso said earlier that investigators were working with the theory that an extermination squad was behind the murders and beatings. Mariano spoke during a religious service for the victims, attended by Justice Minister Marcio Thomaz Bastos, who promised to "bring these bandits to justice." Several hundred people gathered in the center to protest against the killings. --MORE 2324 Local Time 2024 GMT