Police killed 13 people early Monday after a new wave of attacks against authorities on the outskirts of South America's largest city, a state governor said. The killings occurred in the Sao Paulo suburbs of Diadema and Maua, but there was no violence in the city, said state Governor Claudio Lembo. The attacks came a month after a drug and prison gang attacked police stations across the city and Sao Paulo state, initiating a wave of violence that killed nearly 200 police, prison guards, suspected criminals and jail inmates.